If you see a movie in IMAX the movie screens are bigger. The surround sound is greater. You get a better experience in my opinion.
Imax at AZ mills is the largest screen in Arizona (they proclaim, ive not researched myself) but if you enter the mall at the theater entrance on either side, look towards the food court and you will see the Imax entrance as its separate from the Harkins entrance and only has one screen (that is the biggest by far) and fully awesome to see Endgame in 3d!
You have to go to the IMAX theater for the best experience BUT, in the regular theater they most likely have a few screens larger than the rest as is standard for Harkins. I can't recall but I've never had trouble getting tickets.
I don't personally know. Call the theater and they can tell you specifically.
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