Matt Canter at Anchor brewing has a great blog post detailing how each method works and what it does for the beer.

 Nitrogen-dispensed beers give you a creamy mouthfeel, a smoother quality, and push the hoppy flavors down, which allows the maltiness to rise to the top of the flavor profile.

It’s a great quick read if you don’t know a lot about how both dispensing methods work.  Give it a look.