BCY -
452x - The most stable string material, but very stiff.
8125 - The fastest material, but will continue to creep until replaced. This is a very minute amount, but you'll have to add twists on regular intervals to keep it perfectly tuned.
02 - Some where between the two above, but very fast.
Brownell -
S4 and Ultracam - very similar to 452+ only different strand sizes
D75 and D75 thin - very similar to 8125 only different strand sizes
TS1 - very similar to 02
All these materials are made from different grades of Honeywell Spectra or DSM Dyneema as the base material (ultra high molecular weight polyethelene fiber). The tow sizes, colors and treatments (wax) are different, but the base materials are exactly the same from both companies. Both companies make the fiber from the same licence, though I can't remember who came up with it first and licenced the other
The 450 series and S4/Ultracam materials have another fiber called Vectran (liquid crystal polymer) added to stiffen them up. Vectran is the sorce of virtually all the fuzzing that occurs with these materials. It is a very stiff low stretch material and makes for super stable bow strings.
I hope that over view helps some.
Cheers,
Pete