Brutus 20 uses 2 vessels the 10 uses three.
The 20 does not have an HLT.
The difference in the process is that on the 20 you introduce all of your sparge water after the mash, and recirculate it until the sugar concentration is homogeneous and then drain to the BK.
Slightly different, they both make beer. I have a "20", it has a smaller footprint and by default it will keep my sparge PH nice and low.