I can honestly say I never saw a GREEN smallmouth...ever. Now, with these pic's, seeing is believing!
Don't think it's a health issue; both specimens (green and bronze) from these photo's look robust and healthy (except for the small ulceration/injury on the green S/M). So there is something to ponder: that is, why such a big variation in appearance? More probably a result of genetics over time to better aid their survival in their particular home-base water environment...

That's my
uneducated guess, anyway!!

I suppose that could be disproved if you get a greenie and a bronzie out of the same body of water, or at least the same area in a particular body of water if it's a large system. Hmmmmmmm....
W.