Better bonuses and they also give you a higher light level.

For example a raid piece may have a bonus that allows you to do extra damage on enemies that you'll find in the raid thus making it easier when you do it again, also allowing you to get through the raid on hard mode (level 30).

Also got a weapon at the end. Apparently they have primary weapons that have solar, void, and arc damage on them just like your secondary normally has.

Very fun experience. Now if I could only find 5 other people that can commit a few hours without having to leave I could run them through this.