They are quite different lol. CMSF did so many things well and a lot of guys who come and post here just never got the brilliance of it. In my mind, CMSF is still the best combat simulation ever made (Including CMBFN). CMSF was just so hard to balance due to the real world limitations of the Syrians. While I am now an ex-army guy, the modules made life great as you could fight Army units vs the USMC, Dutch, British, Canadian, or Germans and have a nice full on fight that the Syrians just never could have done in the real world. Logically the Allied forces could stand more toe to toe with us.
With CMBFN, there wont be a total superiority factor with the countries involved so your collective minds will not have to wrap around going into a battle with the sole purpose of not losing a single unit.