anchor vs keystone

anchor and keystone both are nouns.

Word	Noun	Adjective	Verb	Adverb
anchor	Yes	No	Yes	No
keystone	Yes	No	No	No

As nouns, anchor and keystone are synonyms defined as:

Other synonyms of anchor include backbone, linchpin, lynchpin, mainstay.

anchor (noun)	keystone (noun)
a mechanical device that prevents a vessel from moving	the central building block at the top of an arch or vault
a central cohesive source of support and stability	a central cohesive source of support and stability
a television reporter who coordinates a broadcast to which several correspondents contribute

anchor (verb)	keystone (verb)
secure a vessel with an anchor
fix firmly and stably