A person’s sex is their biological make up. A female has the two x chromosomes while the male has one x chromosome and one y chromosome. Gender is the mental and social characteristics and aspects that have to do with norms and roles strongly suggested by society.
In one of the episodes in the show Grey’s Anatomy there is a couple at the hospital and the husband is about to undergo surgery to change his physiological anatomy to that of a woman’s. Although his biological sex is male he is unhappy with his gender role and decides to take on the role of a female. Even this is not enough, though, and he decides to change his sex, as well.
This example provides a clear look at the difference between sex and gender, but also looks at how closely related they are. It is also a good example of how a person’s sex and gender affect who they are and what their identity is in society.