OPM resource differentiation as labor and machine

Hello,

We are working on PS implementation at client place. I have defined PS plan and launched it successfully but when I try to open the plan output it is throwing error "Failed to load the input file: 'C:\scp\data_store\4027\EbiPSModel.opz'. This error seems like issue with resource definition. so, I have below questions about resources in OPM.

1) Where can I differentiate if resource is labor or machine?

2) Difference between resource class and resource category?

Also please suggest if this error is related to something else.

Regards,

Mahesh