I think that essentially, Neanderthals and modern man were very close in most respects that any differences between us were minimal indeed - not they were insignificant.
In biology, we have “lumpers” and “splitters”. Lumpers are taxonomists or systematic zoologists who minimize the differences between populations and tend to have a broader definition of a species that includes more individuals despite minor differences in appearance, etc. The Splitters want to emphasize the distinctions and create more taxa.
I think, that when dealing with human populations in the fossil record, anthropologists tend to be splitters. If they were studying populations of say, rats or birds, I think the distinctions would be minimized.
A recent article posted on this forum indicated a new theory is that the European Neanderthals actually died out as a breeding population BEFORE the appearance of modern man. The same article indicated that relict populations of Neanderthals in the Middle East interbred with newly arriving “modern” man and contributed 1-3% of the genes of modern Europeans.
My guess is that if a Neanderthal was given a bath, a shave, taught to speak English and put in a suit, he would just look like a very strong, stocky, rough modern man to the casual observer.
Arnold Schwartzenegger?