MTV sucks in comparison to VH1. But wait - doesn't VH1 play crappy pop videos as well? Aren't they both owned by the same people? Yes - BUT VH1 also has some (by no means all) programming of high quality. Partly, this is due to the fact that many of the documentaries are on MTV. But MTV does documentaries on itself all the time! Yes, this is true. It's the whole idea that VH1 is less biased and presents a more balanced picture of MTV than MTV does of itself, putting MTV in its historical place, but hardly glorifying it the way that it does itself.
As inane as the numerous countdowns on both channels are, VH1's tend to include more of *gasp* events and songs from BEFORE the 80s and 90s, which is (shock and horror) when MTV first started out. What a coincidence!
VH1 also projects a more mature attitude than MTV, which is all about teen and pre-teen exploitation. VH1 doesn't want to alienate its older audience, which actually was alive when the Beatles first broke into the mainstream. Though still "hip" in its style, VH1's pacing is still slower than MTV's, which gives it the time to actually say something of substance in between flashy videos (which are usually less flashy than the typical MTV video).
Also, overall, VH1 plays more videos than MTV and of a greater variety. This is
music television, after all.