Blog hops as I am used to are kind of like a circle of blogs.
Usually there is a theme to the hop. One person starts the hop and links to the next person in the hop, the 2nd person would link to the 3rd and so on until you eventually get back to the starting link.
I never participated but it sounds like alot of work since everyone has to have their post on a given day. The hop usually lasts a day and then you take the link down.
It's done a lot in the crafting circles.
The carnival sounds a little more fun and easy.
Thanks for the link on the carnivals. Now I get it :)