From the early version of the game to the final release, there was not much difference. Some were minor differences such as a cut weapon like the AT4 or more noticeable ones being an original look for the Ultranationalist enemies. In the first trailer for the game, Imran Zakhaev was seen with both his arms in the Coup level. In the final game you would have actually shot one of his arms off.
As Earthwormjim amd SezZ have make us to notice, there are some deleted single player missions still left in the game code:
- Cobra Pilot
- Designated Marksman
- Designated Training
- Helicopter Ride
- Immediate Action
- That’s No Sandstorm
You can read more about these a the Call of Duty Wikia!