The major difference between the 2 gloves is that the TougTek's are waterproof and the Reactor's are not. In the ToughTek's case, the warmth is created by the hand heating up the water, and the glove does not allow the water to escape. The Reactor gloves are not waterproof, but have a titanium lining that reflects heat off of your hand. Both get the job done, but the perfect curves do it with 1mm less neoprene, so there would be a little more dexterity there.
For some reason the ToughTek's seem to go on a little bit easier. The wrist opening is a little bit wider. The Reactor's still go on easy, but the wrist area is a little more snug.
Hope that helps a bit...