is a specific kind of: fern.

is a broader term that covers: licorice fern, Polypodium glycyrrhiza | gray polypody, grey polypody, Polypodium polypodioides, resurrection fern | coast polypody, leatherleaf, leathery polypody, Polypodium scouleri | American wall fern, Polypodium virgianum, rock brake, rock polypody | adder's fern, common polypody, golden maidenhair, golden polypody, Polypodium vulgare, sweet fern, wall fern.

is a member of: genus Polypodium, Polypodium.