Take some chalk and mark the snow tires.
If the tires are identical, rotate them next winter.
If your summer tires are identical, it won't matter which are mounted were, but you SHOULD rotate them. How to tell now is anybody's guess if they weren't marked.
Look in your manual also. If your rims are designed with airflow to cool your rotors, you will have to make sure the right side tires STAY on the right side, and your left side tires....you get the point. I had a CRX that had rims like that. Dunno what you've got, but check your owner's manual.