The transgenderism still remains a phenomenon badly known, difficult to define and to understand, in particular in its relationship with the transsexualism. These two phenomena distinguish themselves one of the other one, and translate each of a modality of relation of the subject to the distinction between the sexes. To expose this subject, this article will present from a historic point of view their emergences, their links and their differences. Then, both modalities of relation to the distinction between the sexes will be analyzed through two clinical case of transsexualism and transgenderism. At the end, it is concluded that the distinction between these two phenomena refers to two abstractions of the distinction between the sexes pushing to a transformation to be understood as a pulsionnal realization by the perception: the transsexualism to base the distinction between the sexes, the transgenderism being rather situated in a narcissistic gender quest independently of the sex.