Besides the added detail (prototypical) they have a big Pittman motor so can likely pull almost twice what a stock K-Line can. They also come with Cruise control. They are hamstrung with two chuffs and a puffer smoke unit like the K-Line. Both can be upgraded to 4 chuffs and a fan smoke unit and K-Line upgraded to Cruise easily.
A New York Central fan would want at least one of each, J1e and J3a. Williams Masterpiece is a J3a as well. All MTH unstreamlined are J1e or J1b by cab number at least if not detail.
The 700E is scale.
This is a good online reference for NYC steam.
https://www.railarchive.net/nyccollection/index.html
Pete