Um, what is with the hostility?
The distinction between sex and gender differentiates sex (the anatomy of an individual’s reproductive system, and secondary sex characteristics) from gender, which can refer to either social roles based on the sex of the person (gender role) or personal identification of one’s own gender based on an internal awareness (gender identity). In some circumstances, an individual’s assigned sex and gender do not align, and the person may be transgender. In other cases, an individual may have biological sex characteristics that complicate sex assignment, and the person may be intersex.
The sex and gender distinction is not universal. In ordinary speech, sex and gender are often used interchangeably. Some dictionaries and academic disciplines give them different definitions while others do not.
Among scientists, the term sex differences (as compared to gender differences) is typically applied to sexually dimorphic traits that are hypothesized to be evolved consequences of sexual selection.
Perhaps discuss these issues and definitions with whichever medical professional(s) are assisting you with your transition?