room vs clearance

room and clearance both are nouns.

Word	Noun	Adjective	Verb	Adverb
room	Yes	No	Yes	No
clearance	Yes	No	No	No

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

room (noun)	clearance (noun)
an area within a building enclosed by walls and floor and ceiling	permission to proceed
the people who are present in a room	the distance by which one thing clears another; the space between them
space for movement	vertical space available to allow easy passage under something
opportunity for

room (verb)	clearance (verb)
live and take one's meals at or in