The difference is more the tube specs than manufacturer I believe. Then there's customer service and warranty. I know TNVC is great to deal with but can't vouch for night ops.
I've bought a few items direct from NightOptics they have always been great to deal with and the systems I bought came with good spec pretty clean pinnacle tubes. TNVC has the L3 Mil-spec tubes for a good price so thats a good system to have.