So I don't know if anyone else has noticed this, but it's fairly simple to find out which one is real. If you look closely this infinity gauntlet is for the right hand. If you can't see that here's a closer look
So anyway, this is for the right hand. At the end of Age of Ultron we see thanos put on his Infinity Guantlet for the first time on his left hand. (Pictured below)
Now that we have that down, your probably wondering how this proves which one is real. Well we need one more picture for that, and here it is.
Now here we a picture with thanos and the real Infinity Guantlet and the real infinity stones; It's on his left hand.
Thanos has the real Infinity Guantlet, which now raises the question: Why does Odin have the fake Guantlet, and does he know he has the fake one?
If you have any questions let me know in the comments!