The korean war, and the first gulf war were formally sanctioned by the UN and international law, as they were reactions to true aggresion: the invasion of south korea, and kuwait respectively. Both wars had broad, international consensus internationally, or in the case of korea, from the free non-communist bloc. Tens of thousands of actual combat troops from dozens of nations participated.
Bush's Iraq war was not formally sanctioned, nor did it enjoy true broad international support. Not even from NATO. While, bush cobbled together some governments to sanction his war, he did not have the world's support or the international legitimacy that would have been helpful, indeed neccessary. And few nations contributed or sacrificed actual combat troops to Bush's war.