I found this:
Dolby Digital transmits at 684kbps and DTS transmits 1,500kbps (1.5mps). The DTS is "less compressed" like everyone's saying and should "in theory" produce superior audio qualtiy. Most people can't tell the difference. These two competing audio formats are the "Coke and Pepsi" of digital surround. Personally, I prefer DTS (and Pepsi), but I'm sure others would disagree.