People identify with their biological sex in various ways. However, sex and gender are two distinct concepts. Sex refers to ones biological sex. Gender refers to the social constructs around sex.
As individuals we seek to expression our preferred or identified gender differently. Some of us are happy to take on the dress and mannerisms of another gender at times, others want to fully transition into living as their identified gender.
Watch this video from Girlfriend TV’s Arielle Scarcella to get a better insight.