Tents are a structure that cover approximately 3/4 of the mattress. They are assembled by you and take approximately 10 minutes per tent. A set-up video is located here: https://www.seattlesleepovers.com/tent-assembly.
Teepees are a pre-assembled structure that form a point at the top. They offer more vertical space, cover approximately 1/4 of the mattress and are recommended for larger parties (less set-up time) and older kids.