They are similar, but different in trigger pull. The glock, as described, feels like it has a longer, more DA feel because the weight throughout the pull is more consistent and doesn't seem to "stack" as much as the XD trigger does. However, i guess it does sort of "stack" a little, depending on how you define "stack", because the Glock trigger pull is actually harder towards the rear of the pull than it is at the beginning. Then right at the rear of the pull, it seems to snap like a single action "click."
The XD has more noticeable stages in the trigger's travel. First stage is light, 2nd stage is a little heavier, then it stops right before the same kind of single action "click" that the Glock has.
In my opinion, after owning 2 Glocks and 2 XDs, the XD trigger is FAR superior. Sure, the Glock was described as "smoother" just because of the consistency in the trigger weight throughout the pull, but in reality the Glock's trigger feel is LESS smooth and solid when compared to the XD pull. The Glock's plastic trigger setup makes the pull feel a bit grindy and unsmooth. The side-to side play is more noticeable on the Glock as well. The ergonomics of the XDs trigger are better IMO. Your finger sits on the trigger perfectly, and when you pull the trigger it comes straight back and the sights stay on target. The Glock trigger is uncomfortable, sharp, and the safety on it feels like total crap when compared to the XD trigger safety.
Overall, i feel that the XD trigger system is far better than the Glock. I actually shoot the XD better than any other pistol I've shot because of how nice the trigger pull is (including my Walther P99 AS which also has a great trigger pull).
You really have to shoot both with live ammo to understand why the XD just shoots better
hope that helps...