[1] In popular usage, "vinyl" refers only to polyvinyl chloride (PVC).
Important examples can be distinguished by the R group in the monomer H2C=CHR: Vinyl polymers are produced using catalysts.
Still others (polystyrene) are produced using anionic initiators such as butyl lithium.
Vinyl alcohol is not sufficiently stable to undergo polymerization.
With the exception of polyethylene, vinyl polymers can arise from head-to-tail linking of monomers, head-to-head combined with tail-to-tail, or a mixture of those two patterns.