Mink are sometimes confused with otters. The most obvious difference is size; the mink is slightly smaller than a domestic cat, while an otter is considerably larger — closer in size to a medium-sized dog.
The tails differ as well. Otters have a stout tapering tail, horizontally flattened, whilst mink have a more cylindrical and somewhat bushier tail.
In coloration, mink are usually dark chocolate brown with a while chin patch; an otter’s coat is mid-brown, with a paler throat and chest.