gaoler vs prison guard

gaoler and prison guard both are nouns.

Word	Noun	Adjective	Verb	Adverb
gaoler	Yes	No	No	No
prison guard	Yes	No	No	No

As nouns, gaoler and prison guard are synonyms defined as:

Other synonyms of gaoler include jailer, jailor, screw, turnkey.

gaoler (noun)	prison guard (noun)
someone who guards prisoners	someone who guards prisoners