Yes, sex and gender are different concepts.
They refer to distinct (though related) phenomena, and the distinction is now standard in medicine, psychology, sociology, law, and most major scientific organizations worldwide.
Here’s the current mainstream understanding, presented side-by-side for clarity:
Aspect
Sex
Gender
Definition
Biological and physiological characteristics
Socially constructed roles, behaviors, identities, expressions
Primary basis
Chromosomes, gonads, hormones, internal & external genitalia, secondary sex characteristics
Internal sense of self + societal expectations and norms
Main categories
Male, female, intersex (DSD)
Man, woman, non-binary, genderqueer, agender, etc. (varies by culture)
How it is assigned/determined
Usually at birth based on visible genitalia (and increasingly prenatal testing)
Develops over time; can be congruent or incongruent with assigned sex
Can it change?
Mostly fixed at conception (with rare exceptions); medical interventions can alter some features
Can change (gender transition, gender fluid people) or remain stable
Scientific field most associated
Biology, endocrinology, genetics, medicine
Psychology, sociology, anthropology, gender studies
Examples of markers
XX / XY chromosomes, testosterone vs estrogen levels, presence of ovaries vs testes, etc.
Pronouns, clothing choices, name changes, gender roles, gender identity
Why the distinction matters / why it exists
They are not perfectly correlated
Most people have a gender identity that matches their biological sex (cisgender).
Some people do not (transgender, non-binary, etc.).
If sex and gender were exactly the same thing, transgender identities and gender dysphoria could not exist in the way they do.
Intersex conditions show biology is not always binary
About 0.05–1.7% of people (depending on definition) are born with differences of sex development (DSD/intersex traits). These cases make clear that even biological sex exists on more of a bimodal distribution than a strict binary.
Many societies recognize more than two genders
Historical and current examples: hijra (South Asia), two-spirit (some Indigenous North American cultures), fa’afafine (Samoa), etc. These are gender categories, not biological sexes.
Medical & legal systems increasingly separate them
Medical records often note both sex (for things like prostate screening, pregnancy risk, drug metabolism) and gender (for respectful care, mental health).
Many countries now allow gender marker changes on documents without requiring genital surgery or even hormone treatment.
Quick summary one-liner versions used by major organizations
World Health Organization (WHO): “Sex refers to biological and physiological characteristics, whereas gender refers to socially constructed roles.”
American Psychological Association (APA): “Gender is a non-binary construct that allows for a range of gender identities.”
CDC / NIH: Routinely distinguish sex (biological) from gender (social/psychological).
So yes — sex and gender are different, because one describes the body you were born with, while the other describes who you understand yourself to be and/or how society expects you to behave.
The distinction isn’t new (it dates back at least to the 1950s in academic work), but it became much more widely known and applied in the 1990s–2020s.