Is this a spotted bass or largemouth? Whats the difference between the two?

I'm goin large mouth. Next time close the mouth, draw a straight line down through the eye and youll see the mouth passing through that line, Large Mouth. Also feel on the tongue and a spot will have a patch of sand paper.

The reason I say LM on that is the mouth size is about what I'd expect to see on a ~12" Spot.

NGaHB

Largemouth all the way. Like GA said, next time close the mouth and if the jawline extends past the back of the eye it's a largemouth, if not it's a spot. The rough patch on the tougue is another clue but I've heard of largemouth having something similar. The dark, solid lateral line is another indicator that you caught a largemouth and not a spot. Spots may have somewhat of a line but not as dark and distinct as that one has.

It looks like a Spot to me, But it's hard to tell in that pic.

Another way to tell a Spot is the scales around it's eye/cheek are smaller then the rest of the body scales, The LMB has the same size scales all over it. The pic makes them look smaller and smoother..

Also the dorsal fins are more one long connected fin on a Spotted bass. The LMB is connected but has a gap between the front and rear fin.

that's a largemouth

Easiest way to tell is if the jaw extends past the eye as already stated. It can be hard if not impossible to determine using coloration, lines/spots and patches on tongue. Here in KY the determining factor is the jaw and not a patch on the tongue; I have seen several fish that look like a cross and seem to have characteristics of both. A patch on the tongue is still often (incorrectly) used for identification and believe it was even used to differentiate in the F&W regs until very recently.