can someone explain me the difference between :

- 2WD standard Oil Pump
- 2WD High Pressure Oil Pump
- 4WD standard Oil Pump
- 4WD High Pressure Oil Pump


I assume the difference between the standard and the high pressure is a harder spring but

- what is the gain to expect with a high pressure ?
- can you put a 4WD oil pump on a 2WD block


thanks