Huge differences.
Romney broke records in spending in the primary, and he had all of the organization and manpower, yet lost against a couple of unfunded, unmanned, weak campaigns, Romney has only managed to win a single election in his 18 years of running, and he left that office a failure with 34% approval, and his hopes for reelection dashed, the democrats took over the seat.
Palin has a proven record of election success, and was the most popular Governor in America, and her effect in this election were history making, Palin's support is deep, and conservative, Romney's is shallow and top heavy.
Palin does not have an "FR bubble", she has the highest favorable approval of all primary candidates.
Now, back to Mitt. You can say what you want about his showing in 2008---when, shall we recall---both Huck and McCain tag-teamed him. But ordinary, average people who are not ideologues like the guy, and his name is ALWAYS among the first to come up with people who don't follow politics on a daily basis---and NEVER Palin's name.
There is a blinder on for Mitt here at FR. It's one thing not to like him or his policies. It's quite another to fail to understand his appeal to a lot (perhaps not a majority, but a lot) of ordinary folks.