Here is a screen shot showing the unfocused spot of a NEJE A40640 40w module. You can see the spot is very square. Not shown here but it is actually burning a spot in the wood at this distance.
Here is the NEJE N40630 30w module at roughly the same distance. Assuming the focus is set roughly the same then it looks from this shot like the spot height is the same as the 40w module but the width is 3x smaller. That should represent a 3x increase in optical power in theory, assuming the FAC lens is not cutting the power down. In practice I suspect between the FAC lens and the beam splitter the laser is loosing 30% power so were probably only seeing a doubling of power here. Coupled with the beam splitter were getting close to 4x more power than my 30w module.
Here is a 20w module, I'm guessing it is the N30820 module. It has a similar spot size to the 30w module and probably uses the same laser diode. Assuming all three were run at the same power percent, then it appears from the brightness of the spots that the 40w module is outputting a lot more power. Someday I will get my hands on one and compare it.
These were all taken from this video