Styrenics are all based upon the styrene compound, which is part of several resin classes. High Impact Polystyrene (HIPS or STY-HI) is opaque and has good stiffness. General Purpose Polystyrene (GPPS or STY-GP) is very clear and can be referred to as crystal styrene. Butadiene rubber, Acrylonitrile, and Acrylate can be added to create resins such as: Acryolnitrile Butadiene Styrene (ABS), a common industrial/commercial material with good impact resistance; Acrylonitrile Styrene Acrylate (ASA); Styrene AcryloNitrile (SAN), Styrene Butadiene Styrene (SBS) rubber; and others. Wikipedia Link