Instead of Snake teaming up with Diamond Dog and the walker, he is instead teaming up this time with Quiet and D-Horse. Just these two changes along would be enough to drastically alter how the game is played but it doesn't stop there. I mean, one of those differences is that you can shoot your arm like a Nikita missile. Again, YOU CAN SHOOT YOUR BIONIC ARM LIKE A GUIDED MISSILE.
You can also sled down hills via cardboard boxes. Also, your horse poops on command.