The following is the explanation of the alphabets in the part number:
F -> the part is field programmable
Z -> the package is TSSOP, default is SOIC
K -> the part is from a new fab location
X -> implies that the part is RoHS 6 compliant (Pb free)
The difference between the parts CY22150KFZXC and CY22150FZXC is only of a fab location and they can be interchangeably used in each other's place.