system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 why is 'Head and Shoulders' shampoo "For men"?

Just marketing, or is there more to it?
gpt
For most 'drugstore' brands of toiletries like shampoo, soap, and deoderant, the only significant differences between the mens and womens versions of products are:

Scent:  since most men don't want to smell like tahitian vanilla and most women don't want to smell like whatever-it-is axe smells like

Price:  you can see this most with razors.  mens products are generally priced lower than womens for the same volume

Color:  most noticeable in the packaging, but occasionally the product itself is colored

Once you get into the high-end 'salon' products, there can be true formulary differences.