On domestic policy issues, I don't think that Obama and Romney will differ all that much. Both men will work towards and almost certainly get a grand deficit-controlling bargain that will largely be limited in scope by constraints imposed by the legislative branch. The Republicans in the house will limit the tax increases, although there will be some. The Democrats will limit the cuts to entitlements, although they will be hefty in either case because they have to be.
The biggest difference between Romney and Obama, in my mind, is when it comes to foreign policy. I don't believe that Romney is a war-monger but I do believe that he will be surrounded and supported by "intellectuals" who are. The Republicans are ITCHING for another war. They want a strike on Iran, they want intervention in Syria. Its madness, but it is the truth.
I don't believe that Romney will initiate these events, but I do believe that those who surround him or those in control of the party will push buttons and initiate events such that the gears of war start turning. Once the machine starts moving, Romney will go along with it. Read this for a sobering reminder of why this remains my single biggest concern for the prospects of a Romney presidency:
John Bolton isn't just any foreign policy thinker in the Republican Party. He is THE foreign policy thinker of the Republican Party.