The difference is Bush wanted to go after terrorist infrastructure, the ability to produce WMD that could fall into the hands of terrorist. These guys really just want to arm the Muslim Brotherhood.
It's been a dream of the MB since the Third Reich to unite all the Arab countries into one large Arab fatherland and I think this is what we are seeing. If the Syrian regime collapses the war will just move onto Iran, then to Saudi Arabia and so forth.
Once all the Arab nations are under one rule that would mean if you attack one nation they all go to war. If a Palestinian state joins the Arab Fatherland and decides to lauch rockets into Isreal and the Isreali's respond that would trigger WWIII.