U.S. vs United States

U.S. and United States both are nouns.

Word	Noun	Adjective	Verb	Adverb
U.S.	Yes	No	No	No
United States	Yes	No	No	No

As nouns, U.S. and United States are synonyms defined as:

U.S. and United States: the executive and legislative and judicial branches of the federal government of the United States

Other synonyms of U.S. include U.S. government, United States government, US Government.

As nouns, U.S. and United States are synonyms defined as:

U.S. and United States: North American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776

Other synonyms of U.S. include America, the States, U.S.A., United States of America, US, USA.

U.S. (noun)	United States (noun)
the executive and legislative and judicial branches of the federal government of the United States	the executive and legislative and judicial branches of the federal government of the United States
North American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776	North American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776