I think you are comparing apples to oranges. One is an M40, one is an m42, which potentially had very different factory paint surfaces and an unknown number of overpaints in between. You're also comparing a textured and non-textured camo, which would have different wear/age properties. Furthermore, you're comparing a helmet that saw a lot of use with one that potentially didnt, and one with thickly applied paint and the other thinly. I also cannot see the liner to judge the amount the helmet was worn (even if i could i also realize it could have been worn for years before being camo'd) but if the M40 had less wear to the liner that would certainly calm some fears. We also have no knowledge of amount of field-use these helmets saw nor how they were stored the past 70 years.
I don't consider myself an expert by any means, which is part of the reason I only buy things cheap and out of the woods, but without hands-on, and with the few pictures shown, IMO both helmets have the potential to be real. Then again, they belong to a dealer so i wouldn't buy either of them.