It has been a long time since I have fired a Glock, so I won't comment on the difference as my memory is fuzzy... BUt I will say a quick blurb about dry firing an HK with LEM trigger:
The trigger can only be properly reset when the slide moves because the movement of the slide semi-cocks the striker. If you are dry firing a LEM trigger with our racking the slide (just enough to reset the striker) then you will notice a much longer reset as the gun is in more of a traditional double action type of mode. If that makes sense at all... That is probably why you don't notice the difference in reset when you are shooting and you do when dry firing. ?