"but I ask myself what's the difference whether they issue Misc or NEC?" That and W2, all have differences.

Without knowing what is "deliver a product" or which type of course or degree is involved (graduate studies? field placement?), one thing that makes the difference is when the person is under a departmental program vs hired by the institution directly. For instance, a Physical Sciences department will have a budget in the chemistry department for a lab assistant. That might be for teaching assistant, providing services, a specific program of study (such as a sponsored testing study) or it can be part of a work-study program. There are stipends, grants and fellowships.

Or, the person issuing the 1099-Misc doesn't know it changed from that form box 7 to a 1099-NEC, years ago.

Not enough information to really explain it more than this. The issuer can be contacted, you know.