difference between 10v & 20v 90q pressure plate ?

[Ben Swann]

Anyone know what the difference between a 90Q 10valve pressure plate

034 141 117D    CLUTCH COVER-PRESSURE PLATE-240mm 
	which fits
      88-92     80/90 5 Cyl.
      88-92     80/90 Quattro 5 Cyl. - 10 Valve
      89-91     100
      89-91     100 Quattro

vs.
 
 90Q 20valve pressure plate

034 141 117B    CLUTCH COVER-PRESSURE PLATE-240mm
      89-92     90 Quattro 5 Cyl. - 20 Valve

?????

Ben