cruise ship vs cruise liner

cruise ship and cruise liner both are nouns.

Word	Noun	Adjective	Verb	Adverb
cruise ship	Yes	No	No	No
cruise liner	Yes	No	No	No

As nouns, cruise ship and cruise liner are synonyms defined as:

cruise ship and cruise liner: a passenger ship used commercially for pleasure cruises

cruise ship (noun)	cruise liner (noun)
a passenger ship used commercially for pleasure cruises	a passenger ship used commercially for pleasure cruises