Gender - sex
Some pedantic teachers insist on distinguishing the two concepts of gender and sex rigidly. Other pedants distinguish them - but in different ways. As so often, your job is to consider the prejudices of your reader(s) and your academic subjects.
- Teachers of languages have been known to insist that gender is a grammatical concept, and is only loosely tied to the biological concept of sex.
- Teachers of social sciences often refer to the problems of women, or of men, as part of Gender Studies. Perhaps they regard the title of sex studies as altogether too biological.
When you are describing biological differences, you are advised only to use male and female. When you are describing the classes of nouns etc, you are advised only to use the words masculine and feminine. In other areas, all four words have different connotations. It is not unusual, particularly in fiction, to describe a woman's manner or dress as 'feminine', or a man's jaw or laugh as 'masculine': but in some sociological studies, you would be condemned for stereotyping.
You may also want to see an account of grammatical gender.