traveller vs carrier

traveller and carrier both are nouns.

Word	Noun	Adjective	Verb	Adverb
traveller	Yes	No	No	No
carrier	Yes	No	No	No

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

traveller (noun)	carrier (noun)
a person who changes location	(genetics) an organism that possesses a recessive gene whose effect is masked by a dominant allele; the associated trait is not apparent but can be passed on to offspring
	a large warship that carries planes and has a long flat deck for takeoffs and landings
	a rack attached to a vehicle; for carrying luggage or skis or the like
	a self-propelled wheeled vehicle designed specifically to carry something
	a person or firm in the business of transporting people or goods or messages
	(medicine) a person (or animal) who has some pathogen to which he is immune but who can pass it on to others
	a boy who delivers newspapers
	a man who delivers the mail
	someone whose employment involves carrying something
	a radio wave that can be modulated in order to transmit a signal
	an inactive substance that is a vehicle for a radioactive tracer of the same substance and that assists in its recovery after some chemical reaction