Actually, they are similar in this respect: both are instances where the US has no right intruding.
Because the situation is not symmetric. I'll explain. One side is adopting a pose which can be described as "universal", while the other isn't.
To say "I'm anti-war" is a pretty "universal" statement, is it not? It makes no allowances for particular exceptions. But that is precisely what the protesters say; they speak in universal terms such as, "war is ALWAYS the last resort", "war is a failure of diplomacy", "war is hell and I'm against it, there has got to be a better way". They are saying, or pretending, that their opposition in this particular case (U.S. military attacking Saddam's ruling regime of Iraq) is something which proceeds from a more general principle, namely, "war is bad and I'm anti-war".
Given this, it's quite fair to evaluate whether, in their past statements, they lived up to the general principles they are pretending to follow. That's where Yugoslavia comes in. Were these "anti-war" folks so "anti-war" in that case? Some of them were, actually. But most of them were not. It's a pretty clear-cut case of hypocrisy.
Now, you simply can't go in the other direction as easily, and this is because the "let's attack Saddam" faction is making no such claim to "universality". It's not like we're saying "let's attack Saddam because war is good" :-) We're saying: let's attack Saddam because the particularities of this situation appear to make it the only course of action.
Bringing up Yugoslavia against this statement is, therefore, irrelevant, unless Yugoslavia and Iraq have something significant in common with respect to the reasons the pro-war folks are giving for attacking Saddam.
What are those reasons? Basically the argument boils down to a pre-emptive strike against a madman who is our enemy, probably has WMDs, and has the type of temperament to use them against us or our friends.
But the preceding paragraph simply doesn't apply to Milosevic (except for the "madman" part). Unless you are prepared to argue otherwise by saying what Yugoslavia and Iraq supposedly have in common. Which is why I asked.