They aren't the same (i.e., sex and gender are not synonymous). But sex also can be conceived of as existing on a spectrum and not as a binary. Sex, like gender, is socially constructed (all categories are). Sex may have to do with "biological facts" or whatever, but it is still an interpretation of these. No matter what mix of primary and secondary sex characteristics one takes to be necessary and sufficient for a person being "biologically" male or female, there are lots of people who don't neatly fit into those categories. The artificiality of this binary is evident in the "medical" interventions (non-consensual genital surgery, etc.) frequently performed on infants to force their bodies to fit into it.
They aren't the same (i.e., sex and gender are not synonymous). But sex also can be conceived of as existing on a spectrum and not as a binary. Sex, like gender, is socially constructed (all categories are). Sex may have to do with "biological facts" or whatever, but it is still an interpretation of these. No matter what mix of primary and secondary sex characteristics one takes to be necessary and sufficient for a person being "biologically" male or female, there are lots of people who don't neatly fit into those categories. The artificiality of this binary is evident in the "medical" interventions (non-consensual genital surgery, etc.) frequently performed on infants to force their bodies to fit into it.