You can do essentially everything you can do on the computer versions, except in a different way. I played Civ 2, Civ 3, Civ 4 and all of the Civ 4 expansions. Essentially, Civ Rev for the Xbox is no different, except they took out things to make the gae quicker, and run smoother.
1) Smaller Tech Tree. This means that simply there isn't as many techs.
2) Religion Free. There is no religion, the AI declare war on you no matter what.
3) No open borders.
4) No Civic options (But you can choose a Government type.)
5) No economical penalty for expansion.
6) Workers are no longer actual units, but are apart of the city.
7) Bonus tiles (Dye, Aluminum, Fish etc..) only require the tech to use them.
8) Units don't require any resource to create, only tech.
9) No UU or UB's.
Now, herr are the things that they did to mkae Civ Rev better (In some ways) then Civ 4.
1) Better Combat. There's over-all better combat in Civ Rev, which I'll explain more about. A) Over--Run Bonus. The over-run bonus is where you can 5* the enemies strength, where you automatically destroy their unit. This means that there's no pikeman vs Tank upset in this game. B) The more Units = No always better. In this game, unlike Civ 4, the more units you have, it may not always be better. It's more guerilla style in this game, more blocking off production, and less of just bringing your 100 units stack to the enemy city, catapulting all their units, then attacking.
2) Better Leader traits. In each different era, your leader gets a different trait, theirs one for the Starting Era, Ancient, Medeival, Industrial and Modern Era. This means that each leader is more complex and each one has a different playstyle then in Civ 4.
This is all I can think of, but Civ Rev is 100% a buy. I had no problem adjusting to Civ 4 as it's not that complex as you make it out to be. Pretty much if you read over the Civilopedia, read the handbook and maybe look up one or two things, you can learn what everything means, what units are good vs other units, what type of specialist economies you can run, etc. I had more of a problem adjusting Civ Rev, because it's not as "dumbed down" as you mkae it out to be. Civ Rev is not a tutorial, it's just a console game. If you have a console, buy it, if you don't get the hell out of this thread.