In the United States, many people do not understand the differences between sex, gender, orientation, etc. It is a commonly held belief that if you know someone's biological sex, then you can make all sorts of general and specific assumptions about them. In reality, human sexuality is significantly more complicated than that.
The following include some of many different categories that make up someone's human sexuality¹:
This is someone's biological sex. This is typically binary - as in male or female - but there are several genetic conditions that would make someone intersex. Gender, not sex determines the pronoun used to describe whether someone is a man or a women.
This describes the gender someone identifies with. Someone can identify as a man, woman, neither or both. Gender identity can be considered a spectrum.
Sexual orientation describes who they are sexually attracted to. This is also a spectrum and that spectrum includes intensity. There are people who feel little or no sexual attraction, which is why asexual is a type of sexual orientation.
Romantic orientation describes the people that you want to have intimate, strong relationships with. For many people, romantic orientation and sexual orientation tend to be similar but that is not always the case. Romantic orientation separates the idea that sex has to be the goal of every intimate relationship. This is especially true for asexual people.
Many believe that sexual behavior should coincide with sexual orientation, which is in fact false. For example, a heterosexual priest can have a heterosexual orientation, but because of their religion and lifestyle, have a celibate behavior.
Gender roles are built by society, not people. The most popular gender roles are masculinity and femininity but as most dichotomies are false dichotomies, this is also a spectrum.
It is important to note that every category described above are independent from each other. For example, a person assigned female at birth can be a man who only has sex with women, despite the fact that he is attracted to both men and women and feels more comfortable in female gender roles. Also, many people move across these spectrums throughout their lives.