challenge vs call

challenge and call both are nouns.

Word	Noun	Adjective	Verb	Adverb
challenge	Yes	No	Yes	No
call	Yes	No	Yes	No

As verbs, call is a hyponym of challenge; that is, call is a word with a more specific, narrower meaning than challenge:

challenge (noun)	call (noun)
a call to engage in a contest or fight	(sports) the decision made by an umpire or referee
questioning a statement and demanding an explanation	a visit in an official or professional capacity
a formal objection to the selection of a particular person as a juror	a brief social visit
a demand by a sentry for a password or identification	the option to buy a given stock (or stock index or commodity future) at a given price before a given date
a demanding or stimulating situation	a method of contacting a person by phone
	a loud utterance; often in protest or opposition
	the characteristic sound produced by a bird
	a request
	a demand
	a demand for a show of hands in a card game
	an instruction that interrupts the program being executed
	a demand by a broker that a customer deposit enough to bring his margin up to the minimum requirement

challenge (verb)	call (verb)
issue a challenge to	rouse somebody from sleep with a call
take exception to	challenge the sincerity or truthfulness of
raise a formal objection in a court of law	consider or regard as being
ask for identification	utter in a loud voice or announce
	ascribe a quality to or give a name of a common noun that reflects a quality
	get or try to get into communication (with someone) by telephone
	assign a specified (usually proper) name to
	utter a characteristic note or cry
	send a message or attempt to reach someone by radio, phone, etc.; make a signal to in order to transmit a message
	order, request, or command to come
	indicate a decision in regard to
	challenge (somebody) to make good on a statement; charge with or censure for an offense
	declare in the capacity of an umpire or referee
	utter a sudden loud cry
	make a prediction about; tell in advance
	lure by imitating the characteristic call of an animal
	present for redemption before maturation
	read aloud to check for omissions or absentees
	order, summon, or request for a specific duty or activity, work, role
	order or request or give a command for
	give the calls (to the dancers) for a square dance
	make a demand, as for a card or a suit or a show of hands
	demand payment of (a loan)
	pay a brief visit
	call a meeting; invite or command to meet
	make a stop in a harbour
	greet, as with a prescribed form, title, or name
	stop or postpone because of adverse conditions, such as bad weather