At some point the neanderthal and modern human lineages diverged. I'm not sure what exactly their most common recent ancestor was (I see some sources suggesting homo heidelbergensis), but in any case I'm interested in the innovative/apomorphic features of neanderthals relative to that MRCA. What new features did they have, and what existing features changed most?
In particular I am not asking how neanderthals differ from modern humans.
This question is partially inspired by popular science pieces (e.g., Human Hands More Primitive than Chimp Hands) discussing human hands, which are essentially basal, vs. chimpanzee hands which are less similar to the common ancestor.