Uhhhhhhhh............ BIG difference.
The Quaife is a true LSD, and is a complete differential replacement. It uses a real gear system to make sure that the wheel with the most grip gets the most torque. It works all the time- both in straight lines and in turns, and it has a lifetime warranty.
The Phantom Grip is NOT a true LSD. It's basically two spring plates that push against the spider gears in your stock differential. When the spider gears start to turn at different speeds, the spring plates in the Random Grip push them against their gear carriers, causing them to bind against it and effectiing some resistance to turning. When you turn your wheel, the Phantom No-Grip just springs the two plates apart, and it doesn't do anything for you. Over time, the Random Shit will cause your spider gears to wear down, possibly causing differential failure. It's not a good thing when a traction system requires your differential parts to be jammed together to function. The PG doesn't work in turns- it only works in a straight line. It would be good for a drag race, but I would be very careful using it, and be aware of the potential hazards associated with it. If you read up on SCC's project cars, I know that one of them has a Phantom Grip in it, and SCC hasn't had any problems with transmission failure. Again, your experience might be different- they didn't install it in a Civic. I don't know what they put it in, but I know it wasn't a Honda.