Terrier dog breed coats may be smooth, wire-haired or "broken." The smooth coat on a terrier is much the same as the coats on many short-haired smooth-coat dog breeds, the wire and broken coats are unique to terriers.
Differences
Wire-haired and broken coats are similar. A dog with a wire coat is covered entirely in long, coarse hairs. These hairs are often unruly and give the dog a scruffy appearance, sometimes even covering his eyes. A dog with a broken coat has rough wiry hairs on most of his body but has smooth fur on his face and head. This gives his face a groomed appearance, making him look a little less shaggy than a wire-haired dog. A terrier with a wire coat that has been groomed using the rolling method, which involves continuously pulling the dead wiry hairs to create a sleeker appearance, is sometimes referred to as having a broken coat. While this is not technically a correct use of the term, it is a widely accepted common use.