The classes of Warships in the Terran armada are. GTGs Gunship, GTC Crusier, GTCv Corvette, GTD Destroyer, GTLD Living Destroyer, GTSB Star Behemoth, and finally GTJ Juggernaut.
As for the size of the ships, Terran Gunships are the size of the Auelos crusier, GSA Cruisers that belong to the Terrans are 15% bigger than the Diemos Corvette. The Terran Corvetts are 75% of the size of the Orion Destroyers. Terran Destroyer's and Living Destroyer's are 15% bigger than the Orion class Ships. Terran Star Behemoths are the size of the Collosus. And the Terran Juggurnaunts are 30% bigger than the Collosus.
Juggernaunt Class ships have only been built by the Terrans so far. And their is only one ship that is currently in the Star Behemoth class.
The human Race is currently constructing one. The size of the ship is the same as a Terran Corvette.