Simply put the shoe on the left has a tongue from a larger sized shoe so the tongue is higher/wider, Has a larger ball pump & release valve.
(Left shoe tongue is creased/curved in these pics though)
Apart from the tongues each shoe is exactly the same in every way (These are a size 11 btw)
The tongue on the left shoe looks like it should have been used in a size 12 (I have a pair of size 12 neon Twilight Zones & the tongue is pretty much the same as the ones in them).
Looks like the RBK factory messed up & put the wrong tongue into one of my shoes.
I picked these up from Europe & the next biggest size they had available was an 8 I think so an exchange is not an option.
I'm hoping to get a partial refund at least.