General:
* Pinniped: This is the scientific order that seals, sea lions, and walruses belong to.
* True Seal: This term is used to distinguish seals from sea lions and walruses.
Specific:
* Harbor Seal: This is a specific type of seal found in coastal waters around the world.
* Grey Seal: Another common species of seal.
* Monk Seal: A rare type of seal found in the Mediterranean and the Pacific Ocean.
* Elephant Seal: These are large seals with a prominent proboscis (nose).
It's important to be specific when referring to a seal, as the term can be quite broad.