trailer vs advertisement

trailer and advertisement both are nouns.

Word	Noun	Adjective	Verb	Adverb
trailer	Yes	No	No	No
advertisement	Yes	No	No	No

As nouns, advertisement is a hypernym of trailer; that is, advertisement is a word with a broader meaning than trailer:

trailer: an advertisement consisting of short scenes from a motion picture that will appear in the near future
advertisement: a public promotion of some product or service

Other hypernyms of trailer include ad, advert, advertising, advertizement, advertizing.

trailer (noun)	advertisement (noun)
a wheeled vehicle that can be pulled by a car or truck and is equipped for occupancy	a public promotion of some product or service
a large transport conveyance designed to be pulled by a truck or tractor
an advertisement consisting of short scenes from a motion picture that will appear in the near future
someone who takes more time than necessary; someone who lags behind