What characteristic defines the head shape of a Cottonmouth, contrasting with the Water Snake?

Answer

Broad, blocky, with a distinct neck

Cottonmouths typically possess a broad, blocky head shape that is distinct from its neck, unlike the Northern Water Snake which has a more slender head.

What characteristic defines the head shape of a Cottonmouth, contrasting with the Water Snake?
venomanimalreptilesnakewater snake