free house vs pub

free house and pub both are nouns.

Word	Noun	Adjective	Verb	Adverb
free house	Yes	No	No	No
pub	Yes	No	No	No

As nouns, pub is a hypernym of free house; that is, pub is a word with a broader meaning than free house:

free house: a public house that is not controlled by a brewery and so is free to sell different brands of beer and ale
pub: tavern consisting of a building with a bar and public rooms; often provides light meals

Other hypernyms of free house include gin mill, pothouse, public house, saloon, taphouse.

free house (noun)	pub (noun)
a public house that is not controlled by a brewery and so is free to sell different brands of beer and ale	tavern consisting of a building with a bar and public rooms; often provides light meals