Is gender the same as sex?

No, they’re different. Sex refers to the chromosomes and physical parts you were born with. Gender is hard-wired into your brain; it’s how you feel about yourself and whether you feel “male,” “female,” some of both, or not much of either. It’s pretty common that these two things will line up – most people who are born and the doctor says “It’s a boy!” grow up to identify their gender as male, and most people who are born and the doctor says “It’s a girl!” grow up to identify their gender as female. Sometimes they won’t line up, though, and that’s also normal.