A polyurethane is any polymer consisting of a chain of organic units joined by urethane links. It is widely used in flexible and rigid foams, durable elastomers and high performance adhesives and sealants, fibers, seals, gaskets, condoms, carpet underlay, and hard plastic parts. Polyurethane products are often called “urethanes”. They should not be confused with the specific substance urethane, also known as ethyl carbamate. Polyurethanes are not produced from ethyl carbamate, nor do they contain it.

got that? right…

A nitrile is any organic compound which has a -C≡N functional group. The -C≡N functional group is called a nitrile group. In the -CN group, the carbon atom and the nitrogen atom are triple bonded together. The prefix cyano is used in chemical nomenclature to indicate the presence of a nitrile group in a molecule. A cyanide ion is a negative ion with the formula CN−. The -CN group is sometimes, less properly, referred to as a cyanide group or cyano group and compounds with them are sometimes referred to as cyanides.

phew! I think you did an okay job bringing it down to the basics of what and why. : )