A polydactyl Maine coon is a Maine Coon in every characteristic and with extra toes. This word means multi-toed with extra-large paws. They can walk through snow more easily, hence another nick-name of snowshoe cat; but most often though, they are simply called polys.
A natural anomaly, the polydactyl dominate gene in Maine Coons is a simple autosomal, meaning not linked to a dominate gene. The Pd gene is a harmless genetic trait that is not to be associated with other anomalies. Because of this, you must have a polydactyl parent to have a polydactyl kitten.