There's a huge difference in content-wise between the 2 tests also. It's not just a matter of cosmetics.
For example, Step 3 is designed to see if you are ready to work independently which means do you know enough medicine to be safe, can you spot critical scenarios, do you understand what is going on with this patient. It's written by NBME and after you've survived 3rd year medical school and your 1st 2 Steps, you'll start to realize that Step 3 has the same question format as all your other tests. By my count, most of the questions are asked in only 5 ways; which makes it easy to study for. Most of the questions are case-based scenarios, which can be helpful if you're in need to visualize a patient you may have seen.
FM boards is a different beast altogether. It's asking whether or not you are capable of practicing medicine at the level of a residency trained physician. Let it be known that the test that you take as a new grad is the same as the test that old fogies practicing for last 100 years will take. More than that, the question formats are different. Some care case based, some are not. Some are pure facts/trivia... either you know it or you don't, and there's no clinical background to clue you in. It's written by the ABFM which makes their questions random and unpredictable. It's more like your in-training exam format. For example, they'll show you a picture of the rash and ask you the treatment, no history, no description of the physical exam, no buzzwords (which the USMLE would have done). Or the ABFM boards will ask you a question and it will list 5 different beta-blockers or 5 different SSRI's, and you need to know the differences/nuances (USMLE doesn't do this).
