When trying to assist the truthfulness of your statement, I think that Indian political participation either way will be probably the largest factor between 2003 and now. And that might be the swing decider, cuz they're so big.
How many other countries sent weapons into Iraq to defend against us? 2003 certainly wasn't a good mark on the United States, but it's already too late to compare the two. Some countries took their ball and stayed home in 2003, but just two days in, the world is providing more useful assistance to Ukraine than anyone ever gave Iraq.
I mean, while I acknowledge that we were wrong, there was at least
some debate if there were WMDs. There was at least
an attempt to bring in the UN and form a broader coalition than just one of the willing. The Russian buildup to this Ukrainian adventure was so ridiculously propagandized that seemingly no one has taken their pretenses seriously. I get that they don't really care about perception, but that might be something they should work on in the 21st century, with the rather incredible power of social media (something that was really just at it's infancy in 2003, so perhaps if it was more well established there would have been a different reaction to the U.S. invasion of Iraq).
Anyway, it doesn't really matter. The issue right now is Ukraine is fighting for her life, and the world at least seems to be warming to the idea of helping, reservedly, when and how they can.
Frankly, it's somewhat embarrassing to type all of this and reflect that the big issue we claimed, in 2003, was a need to not appease dictators, and to stop them in their tracks. We used that line quite handedly against a country with no navy or air force to speak of. It's a much harder thing to say against a foe who could actually strike back. So, please do not mistake all of this for American chest thumping - I'll say for the third time in this thread "I live in a glass house."