Maximus=Intel Mainstream Line
Rampage=Intel Enthusiast Line
Haswell will be Maximus VI probably, then once Haswell-E comes out it'll be a Rampage V.
The difference between Formula and Extreme is minimal, Formula is typically geared towards gamers(4-way SLI/CFX, integrated high quality sound) whereas the Extreme adds more features for overclockers(subzero sense/OC key, etc.).