What is the difference btwn dolby digital and dts?

DTS is less compressed than DD and I believe fully discrete full range multi-channel with less de-emphasized LFE. Thats about all I can remember from my HT days.

Less compression

As usual, a google search (dolby digital dts) can answer many of your questions, but I will save you the trouble.

http://www.timefordvd.com/tutorial/SurroundSound.shtml

Yes, DTS is less compression. However, I seem to vaguely recall thinking some DD movies sounded better than their DTS counterparts, not really sure why that would be though.

Dolby Digital is a 20:1 compression versus 4:1 for DTS, so DTS soundtracks can be full range for each channel if done right, verus Dolby Digital which isn't full range on every channel. But this still depends on whether the DTS soundtrack was mixed correctly.

You really need full range speakers to take advantage of DTS however since you are feeding it full range information.