Norfolk and Norwich terriers are relatively small dogs. Short legs. Border Terriers are recognizable in several ways. The dog's body is relatively small, but the legs are long -- the standard says something about "racy hindquarters"! which goes with those long legs. Borders can be VERY speedy.

And then there is the prized Otter Head.
Be it noted, this is not to be confused with Otterhounds, which are a separate breed. I had not heard of Otterhounds most of my life, I think they are scarce. Rather large shaggy ungainly looking, at least the one walking around at Westminster was.

Border Terriers, however, are sometimes bred to have a head that resembles that of a UK river otter, with the eyes a fair distance apart, and a broad flat squarish forehead. It's a distinctive looking head once you've seen one.