can sombody please explain how oil is controlled

how to check pressures correctly?
is oil controlled by by lp ie suction accumilator or hp via oil sep?
is it one or the other or both i would assume one or the other depending on system design would i be correct in saying this?
how the oil pump works?

is there an lp and hp on the pump.

i understand comp can only go off on oil lp not hp.

how to check the oil pump works?

i dont have any faults i just want a better understanding of oil control.


thanks