Note that Seatguru has never updated the 739, like they did with the 738, to show two versions. I do not know why they have not that.
Seatguru shows four versions of the 738 - the early style with 14 and 18 FC seats (without/with mid cabin lav, respectively) and the newest 16 and 20 seat versions 1-4. Seatguru also shows the two versions of the 777, with 48 or 50 BF seats.