helpdesk vs help desk

helpdesk and help desk both are nouns.

Word	Noun	Adjective	Verb	Adverb
helpdesk	Yes	No	No	No
help desk	Yes	No	No	No

As nouns, helpdesk and help desk are synonyms defined as:

helpdesk and help desk: a service that provides information and assistance to the users of a computer network

helpdesk (noun)	help desk (noun)
a service that provides information and assistance to the users of a computer network	a service that provides information and assistance to the users of a computer network