Is gender something I have? Or, is gender something I do? Or is a gender a group to which I belong?
It depends on who you ask. There are so many definitions.
Perhaps we are born with a gender that, if we’re lucky, matches the gender role which we will express with our gender expression. Gender identity is a superfluous term, as it just means gender.
Or, perhaps we are born with gender identities, that, if we’re lucky, matches the gender we’re expected to do (gender, here, being a verb, as taught to me in my women’s studies classes).
Or maybe we belong to a gender, which has society-given gender roles, which we want to conform to (as humans always yearn to conform), through gender expression.
Or, is gender in itself the set of societal roles and expected behaviors? In which case, gender role is the superfluous term.
Often, the differences in definitions are even much subtler than these.
Yet, so many conflicts can go back and forth forever due to simple difference of definitions for terms. They’ll fight and fight, until they finally realize they’ve been saying the same thing, just in different languages.
Or else, they give up.