A good question submitted to Allison Winn Scotch's site, because I used to always hear the advice that you should study mastheads but that stymied me:

How do I make sense of a magazine's masthead? I understand what beauty and fashion editors are but I don't have a clue about what the other titles actually mean. I'd like to understand for those cases where I can't contact the magazine for the appropriate editor to query, as has happened recently with a major women's magazine. A dozen phone calls and several messages left for the editorial department netted me nothing.

Allison's answer here.