It's mostly in the movement, but there are also some nice improvements to the case and bracelet of the 9937. The 8926 old versions had the Miyota 8215. New ones may have either the SII NH25 or NH35. The 9937 can have one of 2 Swiss movements. An ETA or a Sellita.
Just as an adjunct: I do believe the 8926 and 9910 were the same watch - with the exception being the 8926 is the bracelet and the 9910 being the rubber-strapped version (at least through the NH25 period; I don't know about the 35 now).
Uh huh, thats what they all say. The first one always sets the hook and then comes the upward or is that downward spiral. "Oh one one wont hurt, oh man that is so nice, look at that one:001_tt1:" Out comes the wallet and CC and before you know it you wind up like Patsbosoxfan or me even.:scared: