The core numbers are too similar to give a difference. The covers are where the difference between the two come from. The cover on the Unhinged seems to give a slightly smoother reaction downlane while the HyRoad Pearl is more skid/flip.
For me, the HyRoad Pearl wasn't too great. It skidded too much in oil and reacted too strong in the dry. I changed the surface but that just put it similar to a ball I already had.
From a general standpoint, people seem to like the Unhinged more than the HyRoad Pearl