Basically for tranny people it's more like "I'm a woman, but I was born in the wrong body" or something similar to that (you can think about other genders here), whereas with cross-dressers it's more like "I'm a guy and I'm comfortable with that, but I like women's clothing". Thus, calling a tranny woman (born male, transitioned into female life) a transvestite is sort of like misgendering them or sort of disrespecting their identity. i dont get it