If you are referring to
this post, then the difference is
the gap concept which doesn't only apply to tournaments.
Basically, very often you need only a moderate ammount of equity to attempt a steal if you're the first to act on a pot preflop. But if someone has already raised, you need much more equity in order to continue. If you think about it like this, it makes sense: in the second case, you need a hand that's strong enough to go up against an opponent who likes his hand enough to open for a raise. In the first case, you aren't being put to that test; you're putting your opponents to that test instead.
Just for clarity, "coldcall" means to call someone else's raise when you hhaven't already put any money on the pot on that round. If someone raises to $2 and you call $2, that's a coldcall. If you limp for $0.50, someone raises to $2 and you call the $1.50 more, that's not a coldcall.