Redding reloading dies use a ring of Titanium Carbide instead of the typical Tungsten Carbide to do the actual sizing operation. Redding claims titanium carbide has a rounded grain structure that results in a smoother, slicker finish than tungsten carbide. I use their Pro series for 45 ACP, 41 Magnum, 44 special and 32 H&R Magnum. The Pro series comes with the Profile Crimp die and seperate seating dies, and I use a Lyman "M" die for the expanding operation.
TiN usually refers to Titanium Nitride, which is used as a coating on drill bits etc as well as steel re-loading dies. It's supposed to have all of the benefits of using a carbide insert in the sizing die [no lubing etc], with the benefit of being able to do tapered and bottle-neck cases as well as straight case calibers. The TiN coating is available from CH4D for dies you already have, standard dies from CH4D and they also do custom dies.
http://www.ch4d.com/