Well, one could argue the differences between gender and sex, sex is when we get in the biological matter, you either have chromosomes XY or XX (XXY or XO in intersex cases), but with gender, the things get into a more Sociological, and philosophical, gender as an idea is a mere construct you can shape in order to be who you really want to be, and for that, there is a huge amount of genders and orientations (but i'll leave that to the spectators)
for example, transgender people uses words like "AFAB or AMAB" when refering to their sex or pre transition identity, this means a trans male is identified as AFAB (assigned female at birth) and the opposite with trans woman (amab, assigned male at birth), is what people usually misunderstands, is not that they are not aware, is that people communicate poorly to express their point of views, mostly, out of ignorance.