CFS vs Fibro

As someone diagnosed with fibro, I was wondering what the differences were that causes the label of 'fibro' or 'CFS' to go on. My google search didn't come up with much, other than the tender spots in addition to the pain....which apparently many people with CFS have also.

Is it just if the tiredness, or the pain is more exaggerated, or is there even less of a guideline to go on than that?

Also, do people with CFS get the same rate of "But you're too young to have..." and as I've heard around here "But you're a guy!"?