Yes It matters if you want clear definitions. People here will probably get mad over my definitions if I further lay them out. You know those movies/cartoons/web comics where the main character guy wakes up as a girl one day and then starts freaking out like a freaky friday? Or perhaps he immediately starts checking out his own body naked in the mirror? Well that person just became a trans man/boy. Trans refers to the brain. ‘biologically male/female’ refers to reproductive organs.