Great question. As I see it there are a few key differences:
- NEM uses PoI (Proof-of-Importance) which relies on trusted supernodes (similar to DASH masternodes). This is essentially algorithms deciding trust instead of people. EOS uses delegated-proof-of-stake which would allow users in the network to vote.
- NEM does not seem to allow for consensus re-writing of the blockchain without a hardfork whereas EOS does.
- Most importantly NEM doesn’t provide asynchronous communication or horizontal scaling. EOS aims to provide these as their key differentiation.
I think NEM is a great project, but I think they are tackling very different markets.