Semantics, mostly! I just feel like when I say I’m getting a masectomy, people assume that it’s cancer-related or otherwise life-threatening in a tangible sense, whereas “top surgery” makes it more clear that it’s for ye olde gender biz.
Top surgery is a specific kind of mastectomy that reconfigures the chest into a masculine shape – regular mastectomies prioritize the removal of malignant tissue rather than resulting appearance. Top surgery results in more male-typical “pecks” and usually involves retaining or grafting the nipple back on.
Top surgery = “I don’t want these boobs, make it look like I never had any.”
Mastectomy= “I have too much boob material and/or my boob material is trying to kill me, take some out.”