Playing the blinds with a good (but not great) hand

hehe, i understand that the answer is prob a bit too long

maybe if you have a free time sometime, you could write sort of an article about this spot, would be awesome

All this talk about leading or not leading the flop seems like a good opportunity to ask something I've been wondering about for a while...

Two situations:

1) We open in the CO, button calls, blinds fold.
2) Button opens, SB folds, we call in the BB.

Standard advice seems to be leading lots of flops (and turns) in (1), compared with almost always checking to the raiser in (2). Can someone explain why, referring only to position and ranges after the flop?

(I understand the difference in ranges between the two situations, but not why it implies the difference in strategy.)