Why is Divinity: Original Sin on PS4 so expensive?

As much as I'd love to play Divinity 2, I don't think my modest laptop could cope. So I thought I'd try the first one on PS4. On X-Box One it seems pretty easy to pick up new for around £15-20. On PS4 though, cheapest I can find is £30+ per-owned and in excess of £60 for a new, sealed copy. I can't work out the reason for the price disparity across consoles. Is the PS4 version somehow superior?