Note that gender and sex differ in many cases, as mentioned above.

Size is less helpful unless the species are together, since the sexes of each species also differ in height.

The sexes usually differ, often in the pattern or number of the black markings.

The sexes also differ in terms of how much they fantasize about dominance and submission.

The sexes differ in size with males having a wider head and bigger size.

That is where your sex and mine differ.

The sex of the individuals involved may differ.

In this species the sexes may differ with the female being either light or dark colored.

You know as well as I do that the two sexes don't really differ except in outward form.

The two sexes do not differ in coloration or markings.