Karl Smith doesn't care if Mitt Romney is a liar, a cad, or a prick. He just wants to know what concrete things would be different under a Romney presidency compared to an Obama Presidency. My list is so conventional that I'm afraid it's pretty boring, but here goes. All of this is based on the assumption that if the electorate is pro-Republican enough to elect Romney, it will also be pro-Republican enough to give Republicans control of the Senate.
For the record, there are also several things I think won't happen. Norman Ornstein and Thomas Mann argue in the Washington Monthly that Republicans would eliminate the filibuster, but I doubt it. (And I'd count it as a long-term benefit in any case.) Romney has talked tough on China, but that's just campaign bushwa. He'd quickly find out that his options are extremely limited on this score. On foreign policy more generally, Obama is actually fairly tenacious, despite Romney's bluster to the contrary, and I doubt that Romney would be able to move much further to his right. Dodd-Frank is a question mark. I suspect some would get repealed (or effectively repealed) but not all of it. This couldn't be done by reconciliation, after all. Social Security privatization is a nonstarter no matter who's president. Substantial cuts to Medicare are probably unlikely too. Ditto for comprehensive immigration reform. And Romney's appointments to the Fed probably wouldn't be a lot different that Obama's.
Among big ticket items, what have I missed?