As adjectives the difference between transsexual and transmale
is that
transsexual is (of a person) being a while
transmale is female-to-male transgender or transsexual.
As a noun transsexual
is one who has changed or is in the process of changing their physical sex (because it did not match their desired sex) by undergoing medical treatment such as hormone replacement therapy (hrt) and/or sex reassignment surgery (srs).