Sex is distinct from gender , which can refer to either social roles based on the sex of a person gender role or personal identification of one's own gender based on an internal awareness gender identity. In ordinary speech, however, sex and gender are often used interchangeably. In most individuals, the various biological determinants of sex are congruent, and consistent with the individual's gender identity,  but in some circumstances, an individual's assigned sex and gender do not align, and the person may be transgender. Before the work of Bentley, Money and Stoller, the word gender was only regularly used to refer to grammatical categories. Anisogamy , or the size differences of gametes sex cells , is the defining feature of the two sexes.
What is the difference between sex and gender?
What is gender? What is sex? - CIHR
Sex and gender are different, and it is crucial to understand why. A person typically has their sex assigned at birth based on physiological characteristics, including their genitalia and chromosome composition. Gender, on the other hand, involves how a person identifies. Unlike natal sex, gender is not made up of binary forms. Instead, gender is a broad spectrum.
Sex and gender
Most of us have been raised with pretty simplistic ideas about sex and gender. Namely, that there are two sexes, male and female, and that they align with two genders, man and woman. But with the increased visibility of transgender, gender non-conforming, and nonbinary folks, many people are beginning to understand that the categories of sex and gender are far more complicated. Society typically tells us that there are two sexes: male and female. You may also be familiar with the fact that some people are intersex , or have a difference of sexual development DSD.
Different terms are regularly used in theories of sexuality and gender, for example sex, gender, gender identity, gender expressions, gender roles, sexual orientation. It is important to be clear about the meanings of such terms. Gender is an area that cuts across thinking about society, law, politics and culture , and it is frequently discussed in relation to other aspects of identity and social position, such as class, ethnicity, age and physical ability.