cover vs board up

cover is a noun but board up is not a noun.

Word	Noun	Adjective	Verb	Adverb
cover	Yes	No	Yes	No
board up	No	No	Yes	No

As verbs, board up is a hyponym of cover; that is, board up is a word with a more specific, narrower meaning than cover:

cover (noun)	board up (noun)
the act of concealing the existence of something by obstructing the view of it
fire that makes it difficult for the enemy to fire on your own individuals or formations
a false identity and background (especially one created for an undercover agent)
a recording of a song that was first recorded or made popular by somebody else
bedding that keeps a person warm in bed
a covering that serves to conceal or shelter something
covering for a hole (especially a hole in the top of a container)
the protective covering on the front, back, and spine of a book
a natural object that covers or envelops
a fixed charge by a restaurant or nightclub over and above the charge for food and drink

cover (verb)	board up (verb)
sit on (eggs)	cover with wooden boards
clothe, as if for protection from the elements
protect by insurance
act on verbally or in some form of artistic expression
be responsible for reporting the details of, as in journalism
maintain a check on; especially by patrolling
protect or defend (a position in a game)
hold within range of an aimed firearm
play a higher card than the one previously played
be responsible for guarding an opponent in a game
provide with a covering or cause to be covered
form a cover over
copulate with a female, used especially of horses
cover as if with a shroud
put something on top of something else
travel across or pass over
hide from view or knowledge
spread over a surface to conceal or protect
be sufficient to meet, defray, or offset the charge or cost of
to take an action to protect against future problems
invest with a large or excessive amount of something
help out by taking someone's place and temporarily assuming his responsibilities
provide for
span an interval of distance, space or time
include in scope; include as part of something broader; have as one's sphere or territory
make up for shortcomings or a feeling of inferiority by exaggerating good qualities