I think that one way in which the students' conformity is fundamentally different is rooted in a fear of unknown. To an extent, perhaps Ishiguro is making a statement about all conformity rooting from the fear of the unknown. The students at the school possess this fear to a higher degree in their condition as being harvested clones. For the students, conformity is a confirmation that they are like "everyone else." Their conformity arises from the condition that there is something different about them. If they conform, the psychological comfort offered is that they are not different, but rather the same "like everyone else." In the students' eyes, being different is not a good thing. Thus, the need to conform is driven by an unsettling desire to simply be seen like "everyone else."
Their conformity is driven by the need for acceptance and not negation. In this, Ruth's desire to be a mid- level office worker is understood. An office worker does not raise flags as to difference. Ruth, like the other children at the school, seeks to fight the inevitable difference that defines her being. In doing so, conformity is something accepted as an almost automatic notion of the good.