The obvious contrast: U.S. intervention in Libya more restrained than in Iraq in 2003, but also vastly more effective. Partly this is luck; one could say neither Obama nor Bush knew that much about what they were getting into--despite the daily intelligence briefing, access to more info than anyone has ever had, etc.
But: Obama did a lot better than Bush. First, he intervened when an actual armed rebellion was underway, with the rebels showing great courage and determination, and some success. Bush was hoping to start a rebellion from scratch--or else he believed Ahmed Chalabi's lies about people just waiting for the U.S.,etc. Secondly, Obama didn't make vast promises about regime change or making the world a better place; he simply took practical steps to help the rebels, and cooperate with NATO. Finally, he's not pulling a "Mission Accomplished" stunt.
So Glenn Reynolds, who has been singing Hallelujah over Iraq for 8 years, is very restrained, and finally links to a rather snarky piece in the LA Times. Not very classy.