The "P.mtp" is the trained MTP, in which atomic types of 1, 2 and 3, refer to: C, N and H, respectively, in the LAMMPS input-data.
The "Light_P.mtp" is a MTP with a lower computational cost, which can be used for the large scale calculations at high temperatures.
The "Train.cfg" and "Train.xyz" are the complete dataset in the "cfg" and "xyz" formats. In the "cfg" format, the atomic types of 1, 6 and 7, refer respectively to, H, C and N.