i don't even know why there is a comparison between these RTS (both outstanding games) and CIV IV. they have nothing to do with each others.
it's like me saying i don't like NBA2K9 because i'd rather play football.
Yeah, they really are completely different. RTS has more in common with FPS games than 4x games as they are twitch based, with the exception of the ones that can be paused and orders can be given out.
Personally I don't like many RTS games. This could be because I suck at them, but I think its more that I don't like the lack of complex strategy in them. Min/Maxers chew them up and spit out single strategies that don't require a lot of modification. This unit is good, this unit is bad. This is your build order, this is your research order. Here are the 20 buttons you should push in the first 10 seconds of the game. Took you 11 seconds? You loose (ok, that may be an exaggeration).
I guess a better comparison is that 4X is chess, where RTS is basketball. There is strategy in both, but one is purely a thinking mans game, where the other requires snap decisions.
Anyways, to the OP and Espy, if you haven't played Civ4 give it a try, it is quite possibly the best game of its genre (Gal Civ gives it a run for its money due to better AI). HOMM really isn't all that different, its just a really simplified version of it. But take all the warnings about loosing large chunks of your life. In the games I play it can take me 2-4 hours to complete a single turn in the late game, and there are hundreds to thousands of terms. I have only ever finished a couple of games.
And don't let Ghandi fool you. He's a prick.