I’m by no means an expert. This is simply based on what I’ve read and heard from healthcare professionals.
Body dysmorphia makes a person have a distorted view of themselves that can lead to them taking extreme measure to “correct” something that isn’t really there/isn’t a problem. People who suffer from anorexia often starve themselves as they believe they are overweight/at risk for being overweight. I’ve heard of some looking in the mirror and seeing an overweight person, when they themselves only way 90 lbs.
People with gender dysphoria have don’t have a distorted view of their body. They see that their body is the way it is and this brings about feelings of anxiety and depression since the body does not align with the gender they are. There have been numerous studies concluding that people can have female brains and a biologically male body. There have been arguments as to whether or not gender dysphoria would exist if there were no such things as gender roles or constructs. I believe they would, as does the person in the link below which explains further. Also, there have been autopsies done on transgender people that shows that certain regions of the brain resembled the biologically opposite gender than their own, which sort of kind of proves transgender people have a medical condition, not a psychological disorder.