I think that some more clarity would help here. When I hear of the idea of "school friends," I consider them to be "acquaintances." They are the type of people with whom you are able to freely engage at school over school related matters. A particular class, a specific homework assignment, or even the general timbre of your respective studies are the topics upon which your association is based. The differentiating point between "school" and "real" friendship is that the relationship is predicated only upon school. The association you have is only because of the shared experience in schooling. Outside this realm, there is little, if anything, upon which to base an attachment of emotional investment. It is for this reason I would consider the concept of "school friends" to be akin to professional "acquaintances." I think that school friends are important because they represent one of the first steps to this professional setting. There will be many people in the workplace with whom interaction is based solely on work, and that is part of the dynamics of being in the workplace. In my mind, the idea of "school friends" is a part of this process.