Here is some text from the IGN Head to Head

Rainbow Six is all about teamwork so of course it supports an array of multiplayer options. The PS3 and 360 feature set in the single-player modes are identical and there are only slight changes to the multiplayer options. The main difference being that the 360 version of the game supports 16 players in online and LAN matches while PS3 supports 14 players. How important are the two extra players? It doesn't drastically change the experience but may mean the world to the nitpicky or hardcore.

Both consoles support voice control using a headset and now the PS3 version also allows players to use the camera to map their face onto their character. This level of customization is definitely appreciated but like the last game the results are often a very scary version of the real you.

If only we could all play as a horribly disfigured version of Xbox 360 Editor Nate Ahearn.
Rainbow Six 2 took a nod from some of the other shooters released last Fall and implemented an arcade style experience and unlocking system. The heads-up display now includes an experience counter that increases when players splatter terrorists in a creative or professional manner. As the points add up so does the player's rank along with their ability to access weapons, armor, and decorative clothing. In essence this system replaces Microsoft's Achievements system completely. You'll still get achievement points for completing levels and certain goals (Call me Sam Achievement: 5 headshots in a row using a silenced weapon) and they are mirrored by trophies on the PS3. Both consoles are winners in the category of achievements.

The tiny addition of extra players in multiplayer gives the 360 an edge if only by a hair. Both versions feel fully featured.

Overall
1. Xbox 360
2. PS3

Graphics
On the default settings the 360 version of Vegas looks dull and washed out however after some tinkering with brightness settings I was able to achieve the same overall picture quality on both consoles. The Xbox 360 version has an in-game brightness adjustment while the PS3 version tells you to adjust the television. The PS3 version also only outputs in 720p while the 360 version supports 720p, 1080i, and 1080p.

Graphically, Vegas 2 seems like a step backwards from the original release. Besides the fact that the environments are dull back-alleys, the game seems to have lost the sheen and polish from the first excursion into Sin City.

There are evident frame rate dips on both consoles; and they are slightly more frequent on PS3. Occasionally we've seen textures pop in late and stutters during gameplay also with slightly more frequency on PS3. After playing both versions on a few different televisions the picture quality is nearly identical. Neither game is silky smooth so I expect many sightings of jaggies and claims that one console produces a better image.

Both consoles display obvious flaws in this category but the 360 is slightly better off. This in no way means that you'll have a flawless experience on Xbox, only that the stutters and frame rate problems are less frequent. Perhaps when the PC version ships we'll see a true winner in this category.

Overall
1. Xbox 360
2. PS3

Presentation
The first immediately noticeable difference between the 360 and PS3 is that Sony's system requires a rather lengthy three gigabyte load before starting the game for the first time. This takes about five minutes not including any system updates. This wouldn't be an issue if it improved the load times but overall the PS3 and 360 versions have the same general level load times of about 30 seconds.

The menu presentation is adequate on both consoles with nearly identical options and layouts. You'll see the same FMV overlays and HUD on either hardware right down to the tiny animated squad icon used during loading screens in the last Vegas excursion. Once again, the presentation is similar to the original but with slightly less appeal after considering the lack of upgrades and polish.

Overall
1. Xbox 360 and PS3

Overall
The difference between Rainbow Six Vegas 2 on 360 and PS3 is barely detectable. The only definitive difference is the number of supported players online, but even that hardly affects the gameplay. If you love the series a purchase on either console will put a smile on your face. However, the Head-to-Head series is all about details, so even though the two versions of this game are incredibly similar the 360 version slightly edges ahead due to its smoother frame rate.

Overall
1. Xbox 360
2. PS3