GENDER, is the word that describes your MENTAL identity, which is not correlated to your physical SEX. Words that are attached to GENDER are woman, lady, women, girl, guy, boy, man, men, androgynous (CAN refer to someone's body), and so on. Gender is also correlated with which pronouns you use.
SEX, is the word that describes your PHYSICAL BODY, your GENITALS, which is not correlated to your GENDER. Words that are attached to SEX are male, intersex, hermaphrodite, female, and names of genitals and so on.
I'm sure there's words I left out, but you get the idea.
I'm just starting to get a little peeved, seeing people play word police when they misuse words themselves.