Unfortunately a few people are dead wrong on here about US Navy Seals hand to hand combat training, which is very extensive, and runs along the same lines as a mixed martial artist or 'UFC Fighter" as you call it which is just an over-generalization of MMA fighters around the world. First off, UFC is a company owned by Dana White, not a fighting style or status. UFC Fighters use mixed martial arts which is usually comprised of Kempo Karate, Muay Thai, and Brazilian Jiu-Jitsu, all of which are studied throughly by Navy Seals (IDK about Force Recon)for situations where they might be stranded or unable to use their weapons.
Unfortunately many differences between them would differ their fighting styles greatly. SEALs are used to open land where-as UFC fighters have the cage, which in turn would affect the way they look at combat. UFC fighters also do this specifically for a living which may give them the edge in hand to hand combat as opposed to a SEAL which has to move on to weapons, parachuting, etc.
To set a perfect stage between a SEAL and a UFC fighter (Because I honestly don't know jack shit about Force Recon)lets say for all intents and purposes, the two are fighting over a parking spot and have intense road rage issues. The UFC fighter would immediately run into the fight and go for the knock out whereas the SEAL would probably look for weaknesses in the UFC fighters stance and keep distance (Keep in mind, UFC has rules, war does not). If it turned into an exchange of hits, the UFC fighter might hit harder but the SEAL will probably be quicker to look for good pressure points to quickly end the fight. In my opinion, I believe the UFC fighter would take the fight. There was a story where I live (Las Vegas) about a professional MMA fighter who belonged to one of those organizations putting 4 Metropolitan Police Officers to sleep before they could draw weapons or taze him after he freaked out in a 7-11. If that isn't street fight ability then idk what is.