PPI doesn't mean much, you need to compare pixels per degree. Resolution divided by fov is the clarity you get. Higher PPI just means the screen is smaller, meaningless when you put a lens in front of it blowing it up to 110 degrees fov.
It just means the headset can be smaller since the screen is smaller.
What does matter is whether it's RGB stripe or Pentile (RGBG) display. Afaik both Quest 2 and PSVR2 have RGB stripe, same.
OLED is the big difference, allowing for HDR with absolute blacks.







