So I know a lot of trainings, including many written by trans people, like to separate sex and gender into different concepts. But in my experience they aren’t all that different and are so integrally tied that you can’t actually separate the two. From an external perspective I think sex is what you are assigned at birth because doctors and parents make an assumption about a binary future for you based on your genitals (and sometimes force surgeries on intersex babies if they don’t match that vision because sexual characteristics aren’t binary either). Gender is what people assume about your genitals and often your behaviors and experiences based on visual cues later on. They are just two sides of the same coin. The only real difference is what external markers you are using. When I was born they assumed I was male based on my genitals and now people assume things about my genitals based on signs such as my beard and build.
Well this gets complicated of course when you are trans or nonbinary. You can do a lot to change your external appearance through clothing, hormones, and surgeries. And since sex isn’t actually based on chromosomes since most people have never been genotyped, I think those changes arguably change your sex tangibly as well. I don’t think I am a feminine person with a male sex. I now have breasts and an estrogen dominant body that is clearly and visibly nonbinary now. I would need to make major alterations at this point via surgery to go back to being a male.
So when I see forms that ask me what my sex is, I get annoyed. You can ask me what my sex assigned at birth was as a data point if you need. But my sex and my gender are the same thing viewed from different lenses.
Now internal gender is a lot harder to define but that’s a post for a future day.