fire escape vs staircase

fire escape and staircase both are nouns.

Word	Noun	Adjective	Verb	Adverb
fire escape	Yes	No	No	No
staircase	Yes	No	No	No

As nouns, staircase is a hypernym of fire escape; that is, staircase is a word with a broader meaning than fire escape:

fire escape: a stairway (often on the outside of a building) that permits exit in the case of fire or other emergency
staircase: a way of access (upward and downward) consisting of a set of steps

Other hypernyms of fire escape include stairway.

fire escape (noun)	staircase (noun)
a stairway (often on the outside of a building) that permits exit in the case of fire or other emergency	a way of access (upward and downward) consisting of a set of steps