I'm learning how to use MPI, and am confused on the difference between -n and -np when calling a script. For reference, I am trying to run the script on a Slurm cluster with OpenMPI 3.

For instance, I can run my script like this:

```
mpirun -n 4 --oversubscribe python par_PyScript2.py

```

or like this:

```
mpirun -np 4 --oversubscribe python par_PyScript2.py

```

Can someone describe what these options actually mean?