...more a structures guy than a fuel system specialist...
But for Airbus center fuel tank means center wing box (inside the fuselage), for Boeing the center fuel tank extends to outboard of the landing gear, hence it is significantly larger and closer to the engines. For the 757 the center fuel tank has 1.5 times the capacity of both outer tanks together, for the A320 it is roughly 1/4 (!)
So the same name does not mean the same thing.