If you have the front tires jacked up off the ground one wheel turning is normal! Or for one wheel to STOP turning is also normal.
That is what spider gears in the diff. are supposed to do. Trun off engine park brake on, put trans. in net. turn each wheel any difference?
I mean in the way they turn one harder than the other? Like goodguy said could be a bearing or maybe brake problem.
Might even have to go to the repair shop.