idler vs trailer

idler and trailer both are nouns.

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

As nouns, trailer is a hyponym of idler; that is, trailer is a word with a more specific, narrower meaning than idler:

idler: person who does no work
trailer: someone who takes more time than necessary; someone who lags behind

idler (noun)	trailer (noun)
person who does no work	a wheeled vehicle that can be pulled by a car or truck and is equipped for occupancy
	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