FUEL isn't on it's own blockchain yet so is just a bunch of smart contracts over Ethereum right?
Etherparty is blockchain agnostic, it supports smart contracts on Ethereum and Bitcoin so far and will allow support for more smart contracts enabled blockchains in the future if they are popular and in demand.
This is pretty unique in the space, that's why I am a big fan. FUEL is one token that allows you to run smart contracts on Etherparty on different blockchains.