Adjective for "pertaining to the differences between the sexes"

"Sex differences."

To be more specific, if you mean chromosomal sex, then you can refer to it as an allosomal or gonosomal difference. From Wikipedia:

A sex chromosome (also referred to as an allosome, heterotypical chromosome, gonosome, or heterochromosome, or idiochromosome)...

Of the two statements you present, only "women have better colour vision than men" is ultimately an allosomal difference because your average color blindness is a recessive sex-linked trait. The statement "men have higher testosterone than women" cannot exactly be linked to sex because of various factors such as hormone replacement therapy and hormonal conditions.

I wouldn’t use it in the space in the sample sentence because I find that poor, but to make it quite clear, when discussing sex differences biological scientists use the term:

sexual dimorphism

whether or not there is physical shape involved. This extract from the entry in Wikipedia reflects general contemporary scientific usage:

Sexual dimorphism is the condition where the sexes of the same species exhibit different characteristics, particularly characteristics not directly involved in reproduction

(I provide further evidence in an appendix, as this view has been contested.)

In a modified sentence similar to that in the question I might write:

These are some facts regarding human sexual dimorphism…

as I regard something like ”sexual-dimorphism facts” unspeakably ugly. However, in this case I would be more intelligible to a general audience writing:

These are some specific facts regarding (non-reproductive) differences between the sexes…

So, as often in questions on this list, I do not accept the structural straight jacket the poster wishes to force himself — and others — into.

Appendix: Examples of current usage of sexual dimorphism

It has been asserted that the term sexual dimorphism only refers to difference in physical characteristics, or to these and observable behaviour, but not to the concentration (loosely referred to as ‘level’) of blood constituents such as testosterone. I accept that this scientific term was originally coined and used in such a restricted sense (the term dimorphism dates from 1832) , but this restriction was quite natural as the term was introduced when biology was restricted to physical observations. As techniques for analysing biological features other than by physical observation, the term was applied to differences in such features. Like it or not, this is the contemporary usage in staid academic journals.

I start with a recent example I think pertinent because it refers to a human hormone and appears repeatedly when one searches the literature. However it has the advantage over testosterone that it is not a sex-specific hormone. It is insulin, a hormone produced in the pancreas that regulates the uptake of glucose from the blood, and the absence of which is the cause of type I diabetes. Here is an example:

• Molecular mechanisms responsible for the sexual dimorphism in pancreatic β-cell insulin release (Journal of General Physiology 2022 (sic))

The term is also used in relation to other constituents of blood, such as lipids:

• Sexual dimorphism in intestinal absorption and lymphatic transport of dietary lipids (Journal of Physiology, 2021)

and to cellular constituents of blood, such as cells of the immune system:

• On sexual dimorphism in immune function (Phil. Trans. R. Soc. B, 2008)

And as a parting shot, the geneticists’ favourite, the fruit fly Drosophila melanogaster, provides a feast in the sexual dimorphism of odorant molecules and their receptors in the brain, as evidenced by the title of this article:

• Sexual Dimorphism: Can You Smell the Difference? (Current Biology, 2008)