0.040" is super low! 95% of all players will have difficulty playing without buzz at that action.
When comparing action on one guitar to another guitar, that measurement is only meaningful if both the neck relief and string height at the nut are identical on both guitars. And remember also not to judge by eye, because we just cannot do that well between two similar guitars, never mind two obviously different guitars.
So, unless we can equalize the three measurements (neck relief, action at nut, and action at 12th fret) we must judge by feel, with our eyes closed, and treat each instrument separately.
What tools do you have? Can you measure neck relief? I capo on top of the 1st fret, hold the string down at 17th, and measure at 7th with feeler gauges. Make sure to hold the guitar in playing position as you measure. The sweet spot for most players is somewhere in the 0.006" to 0.012" range (0.15 mm to 0.30 mm). I aim for 0.008"/0.20 mm.