FX and DX

I shoot DX D7100) FX fascinates me but I've always had a little trouble understanding what the real world difference between DX and FX is.  I shoot wildlife and Landscape. I think DX clearly rules in wildlife photography. I'm told that FX would rule in landscape photography. But in the real world, if you were to take identical shots of a landscape with my DX and a FX, where would I notice the difference, if any?