No, the calipers are the same on all JKs in the US.
Most 15" alloys fit no problem. I have some on my 2010 JKU right now.
15" steelies will fit provided that you get some with 3.75" of backspacing or less. Anything higher than that, and the calipers will hit the lip generated by the stamping process (alloys are poured, not stamped, so alloys don't have this issue).
Any 16" wheel will fit.
Every tire shop in the universe gets this wrong because they use a computer that tells them the stock wheel sizes. The smallest stock JK wheel is 16", but it only comes on the sport. Rubis come with 17" wheels and Saharas with 18" wheels.
For anything smaller than that, they can't be sure it'll fit, so they just say no.
But again, I (and many others) on this forum are ACTUALLY USING 15" wheels and have been for a long time. If it can't be done, somebody better go tell my jeep.