Got both in the store.
Compare them quite a bit for my walk in clients.
Depends on your budget and you personal preference.
Everyone notices the difference. Most also notice the price difference.
Those who want the best, walk out with the Aimpoint.
Those who want to save money, walk out with Vortex.
That said, I run a Vortex 1-4 PST on my AR instead of an Aimpoint, mainly because I like the very quick 4x mag option.
There is a difference, and it come down to money or quality.
Which do you want to have?
Both also have wicked warranties.