Bobtail and Sheep dog

Bobtail noun - Large sheepdog with a profuse shaggy bluish-grey-and-white coat and short tail; believed to trace back to the Roman occupation of Britain.

Sheep dog and bobtail are semantically related. In some cases you can use "Sheep dog" instead a noun "Bobtail".

Sheep dog noun - Any of various usually long-haired breeds of dog reared to herd and guard sheep.

Bobtail and sheep dog are semantically related. Sometimes you can replace term "Bobtail" with "Sheep dog", this terms are similar.