Cases: 2

4x4 parity occurs on the last layer of a 4x4, where you get a case that is impossible to get on a 3x3 so you need a specific algorithm to solve it. 

 

PLL Parity2
PLL Parity2

R' U R U' r2 U2 r2 Uw2 r2 u2 U R' U' R

PLL Parity1
PLL Parity1

r2, U2, r2, Uw2, r2, u2


4 X 4 Related Algorithm Sets