rv garage

OSB would be a lot cheaper but NO fire protection if that's an issue if there is something close by. I would go OSB in shop area and drywall elsewhere.

OSB is not fire retardant unless you order it special for that.
Sheetrock is naturally fire retardant.

Another vote for the OSB, for the reasons gbopp mentioned above. Good Luck and Happy Camping !!

Congrats on your new (to be) garage.
I think the wall covering is a matter of preference. I like OSB or Plywood on the walls because you can nail or screw into it for hanging tools, etc..
But, in my opinion, the sheetrock looks better. I would go with OSB because it's more practical.
Consider going with 3/4 inch plywood or OSB rather than 1/2 inch.
It costs a little more but makes a solid wall. JMO

You can always go back later and cover the OSB with sheetrock.

I don't know about the OSB being fire retardant like sheetrock.