Interests differ primarily on the content, it determines their social value. One interests are directed to social work, science or art, another one - in stamp collecting, fashion; it is certainly not equal interests.
In the interest of a particular thing we usually distinguish between direct and indirect interest. Indicate the presence of a direct concern when the student is interested in the study, the subjects we teach when it is driven by the pursuit of knowledge; talk about indirect interest, when that is not aimed at knowledge as such, but on anything associated with it, such as the benefits which can give educational qualification. The ability to show interest in science and art to the public the case regardless of personal gain is one of the most valuable properties of the person. However, it is absolutely wrong to oppose a direct interest and the interest indirectly. On the one hand, every direct interest usually mediated awareness of the importance, significance, value of the subject or of the case; on the other hand, equally important and valuable than the ability to show interest-free personal benefit is the ability to do a job that is not a direct concern, but is a necessary, important, significant public. Actually, if you really understand the significance of the case that you do, it in effect this will inevitably become interesting; thus, the indirect interest goes direct. 
Interests, then, may vary according to the levels of organisation. Amorphous level is expressed in generalized, not differentiated, more or less easily excited (or excited) interest to all in General and nothing in particular.
With coverage of interests related to their distribution. Of some interest is entirely focused on any one subject or narrowly limited area, which leads to one-sided development of the personality and is together with the result of such one-sided development. Others have two or even several centers, around which are grouped their interests. Only in a very successful combination, namely when these interests are quite different fields (for example, one - in activities, or science and the other in art) and vary greatly in strength, this бифокальность interests causes no complications. Otherwise it can easily result in ambiguities, which will slow down activity both in single and in a different direction: the person did not enter a whole, with a genuine passion, and never succeed. Finally, it is possible for the position in which the interests are wide enough, and multilateral, concentrated in one area and it's so related существеннейшими parties to human activity that around this single rod can regroup a rather complicated system of interests. It is this structure of interests is clearly the most favourable for the comprehensive development of personality and however, the concentration, which is necessary for successful work. 
Different coverage and distribution of interests, which are expressed in a particular latitude and structure, combined with one or another of their force or activity. In some cases, the interest can only be expressed in some preferred direction, or state of being turned, personality, due to which a person is more likely to pay attention to one or another subject, if he's in addition to his efforts to occur. In other cases, interest may be so strong that people actively looking for him satisfaction. We know many examples (M.V. Lomonosov, A. M. Gorky), when interest in science or art by the people who lived in the conditions in which he could not be satisfied, was so great that they rebuilt their lives and went to the greatest sacrifice, just to satisfy this interest. In the first case we speak about passive, in the second - about an active interest; but passive and active interests is not so much a qualitative difference in the two types of interests but rather allow a lot of shades of quantitative differences in their power or intensity. True, this is a quantitative difference, reaching a certain moves in quality, which is expressed in the fact that in one case the interest is only involuntary attention, in the second it becomes a direct motive for practical action. The difference of active and passive interest is not absolute: passive interest easily switch to the active and Vice versa.
The power of interest often, though not necessarily, combined with its sustainability. The very impulsive, emotional, unstable natures happens that an interest until it dominates, is intense, active, but the time of his domination of short duration: one interest quickly replaced by another. The stability of the interest expressed in duration, during which it retains its force: a quantitative measure for the stability of interest. Associated with the force, resistance interest basically is determined not so much by it as depth, i.e. the level of connection of interest with the content and properties of the individual. Thus, the first prerequisite for the very possibility of the existence of man stable interests is the presence of the person rod, General life line. If it is no, no and stable interests; if any stable will be those interests that are associated with it, part of expressing, partly forms.
The interests, usually related in bundles or, rather, in dynamic systems, are like slots, and depth, as there always are basic, more General, and derivative, more private. More General interest is usually more stable. 
The existence of such General interest does not mean, of course, that this interest, such as painting, music, always up to date; it only means that he easily becomes so (you can actually get interested in music, but at this moment do not feel the desire to listen to her). General interests - latent interests, which are easily updated.
The sustainability of these common generalized interests does not mean for their conservatism. Precisely because of their генерализованности sustainability common interests can blend perfectly with their problems, mobility, flexibility, variability. In various situations the same common interest serves as different, in relation to the changed circumstances. Thus, the interests of the General orientation of the individual form a system of moving, changing, dynamic trends moving the center of gravity.
Under the structure of interest we understand the direction, intensity, allocation of interest, on which basis it is possible to follow the dynamics of its change depending on various factors. 
In modern Russian psychology problem of interest is considered from the standpoint of the theory of activity, the foundations of which were formulated in the writings of PS Vyhovsky, С.Л. Rubinstein, A.N. Leontiev. All activities are closely interrelated, and the greater the extent to older adolescent, boy, girl are the subjects of different activities, so obviously intensive is their socialization individualization.
PS Vygotsky thoroughly examined the issue interests in a transitional age, calling it "the key to the whole problem of the psychological development of a teenager. He wrote that all psychological functions of the human body at each stage of development, including in adolescence, are not haphazardly, not automatically, and not by accident, but in the certain system, directed to specific, отложившимися in the person of aspirations, inclinations and interests. In adolescence, emphasized PS Vygotsky, a period of destruction and the withering away of the old interests and the period of maturation of new biological basis on which subsequently develop new interests. He wrote: "If at the beginning of the development phase of the interests of stands under the sign of the romantic aspirations, the end of a phase marked by a realistic and practical choice of one of the most sustained interest, for the most part directly connected with the main life line, elected teenager". 
L.I. Bozovic also noted that by the beginning of the age of transition in General mental development of new, broader interests, personal interests and the desire to take a more independent, more "adult" position in life. However, puberty still no possibilities (neither internal nor external to take this позицию.Л.И. Bozovic believed that the divergence between the emerging needs and circumstances of life, limiting the opportunity of their realization, characteristic of each of the age of crisis. But nevertheless, whatever the subjective (and sometimes objectively) nor was life as a teenager, he's still in his whole being is directed towards the future, although "the future is still very vague". Describing adolescence, L.I. Bozovic wrote: "during The period break down and rebuilt all the former child's relationship to the world and to himself. and developing processes of self-consciousness and self-determination, resulting in the end, to the same position in life, with which the pupil starts its independent life".
With the motivational sphere is closely connected moral development of the student who provides substantial changes it is in a transitional age. As wrote L.I. Bozovic, "expressing a certain relationship between people, moral norms are implemented in any activity that requires communication, production, scientific, artistic and other" child acquisition of moral sample comes he commits the real moral actions in significant situations. But the assimilation of the moral sample does not always go smoothly. Performing various actions, teen and more absorbed by the private content of their actions. "As a result, wrote L.I. Bozovic, - he becomes accustomed to behave according to the private sample, but cannot realize its generalized moral sense." These processes are very deep, so often the changes occurring in the area of morality, remain unnoticed neither parents nor teachers. But in this period there is a possibility to correct pedagogical influence, because due to "insufficient generalization of the experience of" moral convictions teenager are still in a fragile condition. Another tumor that occurs at the end of the transition period, L.I. Bozovic called "self-determination". From a subjective point of view it is characterized by an awareness of themselves as members of society and made concrete in the new socially important position. Self-determination occurs at the end of school, when a person has to solve the problem of their future. Self-determination differs from the simple forecasting their future life from dreaming about the future. It is based on the already steadily existing interests and objectives of the subject, involves its capabilities and external circumstances, it is based on forming the worldview of youth and connected with the choice of profession. But genuine self-determination, as expressed by L.I. Bozovic, does not end at this time, it "as a systemic tumor associated сформированием inner attitude of the adult, occurs much later and is the final last stage of ontogenetic development of the child". And at the end of the transitional period of self-determination is characterized not only by understanding yourself, your abilities and aspirations, but also understanding its place in human society and our purpose in life.