public house vs pub

public house and pub both are nouns.

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

As nouns, public house and pub are synonyms defined as:

public house and pub: tavern consisting of a building with a bar and public rooms; often provides light meals

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

public house (noun)	pub (noun)
tavern consisting of a building with a bar and public rooms; often provides light meals	tavern consisting of a building with a bar and public rooms; often provides light meals