the answer is "both" and it depends on where you are working as to what the duties are and what the income is there.

I once worked for a construction company where an executive assistant was a man's job and was like an assistant to the assistant (assistant to the vp) which was a joke of a job yet it paid better than the office manager. I've also seen that in the banking industry except that that title meant you did most of the boss' work but still it was a male's job.

An office manager can be male or female but these days it's more of a female job, and although you do do a lot of things, you also take a lot of guff It's been downgraded over the years.