Harp seal and Hair seal

Harp seal noun - Common Arctic seal; the young are all white.

Hair seal and harp seal are semantically related. In some cases you can use "Hair seal" instead a noun phrase "Harp seal".

Hair seal noun - Any of several seals lacking external ear flaps and having a stiff hairlike coat with hind limbs reduced to swimming flippers.

Harp seal and hair seal are semantically related. Sometimes you can replace phrase "Harp seal" with "Hair seal", this phrases are similar.