They are all essentially the same ship class. The Colorados being, essentially, Tennessees with their four triple 14 inch gun turrets replaced with four twin 16 inch gun turrets. But aside from that, they are, basically, the same ship class. Most improvements to either class was done to both classes, and in the 30s they were referred to as the "Big Five", as they were America's five largest battleships (the Fast Battleship had not been built yet).
These were also the five older battleships that were retained in reserve, post-war until 1959.
