In New York, any vehicle designed, maintained, or used primarily for the transportation of property or for the provision of commercial services is considered a commercial motor vehicle in that state. That's for vehicles registered in New York.
Vehicles from other states operating in New York having commercial or equivalent registration plates from other states or countries shall not be deemed trucks or commercial vehicles unless they are permanently altered or designed primarily to haul freight and marked on the sides with commercial lettering, such as DOT numbers.
So if you are from out of state and have an unmarked cargo van, even if you have "commercial" plates, you can get away with driving on a parkway.
I lived in Jersey for a couple of years, and made many trips to JFK. You cross the Verrazano-Narrows bridge, jump on the Belt Parkway, and you're there. When I started expediting, I made probably 20 round trips to JKF using that route, never once having it dawn on me that the Belt Parkway was an actual parkway instead of it merely being the name of the road.
The last time I was on the Belt Parkway, I got a "NO CMV ON PKWAY NYC" ticket. $120, no points, same as an equipment violation. At least they make it easy for you to plead guilty and pay the fine online.
Cop told me straight up that if I didn't have lettering on the doors of the vehicle, he'd have never pulled me over. Commercial plates, lettering, and no passenger seats rearward of the drivers seat, if all three of those are true, stay off the parkways.