Americanism vs nationalism

Americanism and nationalism both are nouns.

Word	Noun	Adjective	Verb	Adverb
Americanism	Yes	No	No	No
nationalism	Yes	No	No	No

As nouns, nationalism is a hypernym of Americanism; that is, nationalism is a word with a broader meaning than Americanism:

Other hypernyms of Americanism include patriotism.

Americanism (noun)	nationalism (noun)
a custom that is peculiar to the United States or its citizens	love of country and willingness to sacrifice for it
loyalty to the United States and its institutions	the doctrine that your national culture and interests are superior to any other
an expression that is characteristic of English as spoken by Americans	the doctrine that nations should act independently (rather than collectively) to attain their goals
	the aspiration for national independence felt by people under foreign domination