You'll have to elaborate on what you mean by define?
The P-01 and P-06 are essentially the same gun in different calibers. The P-01 has been both marked with a NSN and has not, I don't think the P-06 has ever been NSN marked. I don't think the SP-01 has ever had the NSN number stamped either. There is really no difference between and NSN or not regardless. The P-01/06 utilize the action same parts as a 75BD. The P-01/06 have light rails vs the PCR/75D variants that do not. There are steel frame P-01 compact variants with a light rail but they are?/were not consistently produced.
If the slide is stamped P-06 then it most likely is what your after, there are far less variants available in 40 S&W.
Cheers,
Toby