Terms like sex, gender, gender identity, gender expression, and sexual orientation are often used interchangeably—and just as often, incorrectly. And while it might seem like semantics, understanding the difference between them isn’t just a matter of being politically correct. It’s about showing respect for people’s identities, including your own.

“Sex is biological, gender is social,” says Deborah J. Cohan, PhD, associate professor of sociology at the University of South Carolina Beaufort and the author of Welcome to Wherever We Are: A Memoir of Family, Caregiving and Redemption. “Gender is the social significance given to biological sex differences. It becomes the overlay of expectations and values.”

Of course, even that only scratches the surface. These terms reflect different aspects of who someone is—how they feel, move through the world, express attraction, and want to be seen.

“People often conflate sex, gender, and orientation into one identity marker,” says Zoe Stoller, a social worker and educator who specializes in gender and identity. “But they’re three completely different aspects of who someone is.” Stoller adds that learning the distinctions is one of the easiest ways to show up for people in your life with gender-diverse identities. “You don’t need to be perfect—just open, curious, and willing to learn.”

Think about it this way: People are assigned a sex at birth based on their anatomy. “Gender, on the other hand," Stoller says, "is self-defined. You are the only person who can determine your gender.”

Still with us? Good. Because ahead, we're breaking down the key differences between each term—so you can feel more confident in your language, support your people, and maybe even better understand yourself.

How Sex Is Defined

When it comes to sex, it is not just about the physical act of having it. Sex is also used to describe the biological component that directly correlates with the genitalia you're born with. For example, if you are born with a penis and have XX chromosomes, you are identified as a male on your birth certificate. If you are born with a vagina and have XY chromosomes your birth certificate will be labeled as female.

This is why you may hear people use the phrase "assigned at birth" when speaking about their sex. As Stoller explains, “Sex is something that is ‘assigned’ to people, often by medical providers, while gender is solely self-designated. You are the only person who can know your gender.” There are also intersex folks who are born with variations in their sex traits, and may have traits that don't fit into a male-female spectrum at all. In fact, according to interACT, an organization that works to empower intersex youth, there is no one way to "look" intersex—every person is different, and there are over 40 medical terms for different ways sex anatomy might develop.

The Difference Between Sex and Gender

Just because you are labeled one way on your birth certificate doesn't mean your gender identity or gender expression will match. Remember, gender is a performative social construct. It is tied directly to the ways in which people express themselves and their innermost concept of self.

So the most significant difference is this: Sex is biological and something that you're assigned at birth. Gender is a social construct that each of us gets to decide based on what we know to be true for ourselves.

People who do identify with the gender they were assigned at birth are cisgender. "If you were born with a vagina and identify as a girl/woman or were born with a penis and identify as a boy/man, this means that you are cisgender,” Dr. Cohan said.

But for people who are transgender, this means their sex assigned at birth does not match their gender identity. There are other categories of identity as well, such as non-binary, which generally means a person doesn’t identify with being defined as male or female. Folks sometimes also use the term gender fluid, which means that someone’s gender can morph and may be different at various points.

Keep in mind that there are countless ways to express gender, and there is no right or wrong way to do this. Stoller, who is gender fluid, adds that “each person has the autonomy and agency to decide for themselves what their gender—or lack thereof—means and looks like. It doesn’t need to fit within society’s expectations.” There is no roadmap about how to experience this, and each person’s journey is different.

If you’re wondering about your own gender identity, Dr. Wise, who is transgender, notes that there is no need to rush to put a label on yourself. It’s okay to take your time or change the way you describe your gender over time. “There is so much space to be an individual,” he says. “[Gender] ends up being one factor about you and not your whole defining exhibit. There is no rush to figure it out, and you don’t have to limit yourself.”

What Sexual Orientation Means

When it comes to understanding these larger concepts, it is important to remember that someone's gender and sexual orientation are not the same thing. Gender is, again, a social construct tied to personal expression, while sexual orientation is defined as who you are attracted to. One is not contingent upon the other.

Some examples of someone's sexual orientation might be gay, lesbian, bisexual, queer, etc. and this has nothing to do with their gender identity, which may be cisgender, transgender, non-binary, gender fluid, etc. Sexual orientation is solely based on who you are attracted to (which is *also* different from your romantic orientation, FYI).

Gender Expression

While someone’s gender expression or presentation—which includes everything from their style of dress, mannerism, interests and other elements—may suggest to you that they look a certain way, they in fact may identify in another way. Part of the reason people sometimes struggle with this idea has to do with the larger concepts of gender norms and what is deemed as “masculine” and “feminine." Especially because of the stereotypes that surround this concept—like that only women only wear dresses and only men wear suits.

The best thing you can do is not assume someone's gender expression or identity based on how they may appear to you. Even if someone has a more masculine, feminine, androgynous look, or a combination of these, their gender expression isn’t tied to their sexuality. “Gender expression is about presenting yourself in the way that feels most affirming to you,” says Stoller. “It’s not about meeting someone else’s expectations—it’s about your own comfort and authenticity.”

That is why it is important to meet people where they are and ask them for their pronouns. This can help you better understand them and also respect the person you're with.

How to Become a Better Ally

While you may not identify as transgender, queer, gender fluid, etc., you can still bring attention to issues surrounding these groups by helping to amplify their voices and existence as human beings.

Educating yourself is one way to become a better ally. Stoller suggests that “you don’t need to get the language perfect—just be open to learning and willing to course-correct when needed. Ask respectful questions and stay curious.” Learning about these larger gender concepts and being aware of how you view these things in relation to one another and the world is important. There are lots of resources online and through social media that can help you learn to be more inclusive, like GLAAD, The Trevor Project, and interACT.

It can also be helpful to refrain from using gendered phrases such as “guys" and "girls" when referring to groups, and instead using language like “everyone," "everybody," or "folks” instead. Again, you can also ask people what their pronouns are and how they identify when meeting them for the first time.

Financially contributing to specific causes is also another great way to be an ally. There are lots of organizations and causes that take donations, such as The Trevor Project, The Human Rights Campaign, and others. Doing a search for gender-based groups in your area and seeing which ones you want to contribute to or even volunteer at can also help you make a bigger impact in your own community.

Lastly, one of the biggest ways you can be an ally is to not make assumptions about people in general. Be mindful, educate yourself, ask questions, and support people in the ways they need.