There were three ships of the Maine Class, Maine, Missouri, and Ohio built between 18990 and 1904 at three different shipyards.  They were armed with four 12-inch guns in two twin turrets forward and aft.  The secondary armament was sixteen 6-inch guns located amidships and forward casements.  The easiest way to distinguish these ships is the two twin 12-inch gun mounts, three funnel stacks, and the lower fantail of the ship aft with no gun casements.  If you compare this with the deck and configuration of the Connecticut Class, you see the aft mount is lower and there are not casement gun mounts on the stern.  Additionally, the Maine Class only has two casement guns on the upper row amidships, Connecticut has three casement guns at this location.