Enkephalin Shop
You gain Enkephalin by surviving rounds and will be consumed on purchase. Enkephalin or items in this shop are not saved.
Survival Shop
You gain Survival Points by surviving rounds, but will stay to you after the purchase. SP or items in this shop are saved.
Event Shop
Special items with special requirements. Once acquired, they are permamently unlocked in your save. It's pretty cool.
Special Items
Special items that are not found in the store or not accessible at all.