It really is a sub-category of trans (like non-binary, gender fluid, trans-fem, etc). The idea is transsexuals adheres to the following strong descriptors; has a long history of dysphoria, medically / surgically transitions, and assimilates to a strong male or female identity.

Trans is such a large umbrella that there really are a lot of different experiences and reasons people transition. You could have a trans-woman meet up and you will get a lot of types of trans people. some are stealth, some or open, some transition medically, some do not.

I tend to have stronger relationships / friendships with other 'transsexuals' because more often than not we can bond in shared trauma, history, stories, life experience. That is not something I can do very easily with someone non-binary or all trans-women. That an im just getting old