foreigner vs alien

foreigner and alien both are nouns.

Word	Noun	Adjective	Verb	Adverb
foreigner	Yes	No	No	No
alien	Yes	Yes	Yes	No

As nouns, foreigner and alien are synonyms defined as:

foreigner and alien: a person who comes from a foreign country; someone who does not owe allegiance to your country

Other synonyms of foreigner include noncitizen, outlander.

As nouns, alien is a hypernym of foreigner; that is, alien is a word with a broader meaning than foreigner:

foreigner: someone who is excluded from or is not a member of a group
alien: anyone who does not belong in the environment in which they are found

Other hypernyms of foreigner include stranger, unknown.

foreigner (noun)	alien (noun)
a person who comes from a foreign country; someone who does not owe allegiance to your country	a person who comes from a foreign country; someone who does not owe allegiance to your country
someone who is excluded from or is not a member of a group	anyone who does not belong in the environment in which they are found
	a form of life assumed to exist outside the Earth or its atmosphere

foreigner (adjective)	alien (adjective)
	not contained in or deriving from the essential nature of something
	being or from or characteristic of another place or part of the world

foreigner (verb)	alien (verb)
	transfer property or ownership