The former is a Public Works Project that you can place anywhere in your town, where villagers will sometimes appear. The latter is managed by Harvey, where the two RVs will park. The first one switches on a daily basis, while the second one is summoned when you use an eligible amiibo via Wisp's lamp or during an event by using the campground's Wi-Fi.
Normally, inviting any amiibo character will have its own RV immediately appearing on the campground and rewards you 5 MEOW tickets. Meaning that as soon as you invite anyone with Wisp's lamp, be sure to visit the campground the same day you used the amiibo, and not the campsite.