Both models can presumably be used on a PS4. The Pro X headset is equipped with Blue Voice and DTS X 2.0, which is not the case with the Pro. The delivery content is also different:
Pro X: Gaming headset, Leatherette ear cups with memory foam, Fabric ear cups with memory foam, External USB sound card, Detachable microphone, 2m cable with integrated volume and mute controls, Mobile phone cable with button
Y-splitter for separate microphone and headphone ports, Carrying pouch
Pro: Gaming headset, Leatherette ear cups with memory foam, External USB sound card, Detachable microphone, 2m cable with integrated volume and mute controls, Y-splitter for separate headset and microphone ports, User documentation