Well, it's not like the DLP one where it has loops and stuff, but it is a VERY different ride.
1. Seating arrangement: DL's seats 2 by 2, 3 rows per rocket, 2 rockets per train. WDW's as you know seats 1 by 1, 3 rows per rocket, 2 rockets per train.
2. Audio: Plain and simple. DL has music programmed to match the ride, WDW's doesn't.
3. Smoothness: DL 436890x more smoother than WDW's. Just leave it at that.
4. Darkness: During DL's Space it is nearly impossible to see what's in front of you. On WDW's Space there are some points (though not many) during the ride where there are lights and you can see what's coming up.
All of these 4 combined make DL's far superior to WDW's Space.