stairway vs staircase

stairway and staircase both are nouns.

Word	Noun	Adjective	Verb	Adverb
stairway	Yes	No	No	No
staircase	Yes	No	No	No

As nouns, stairway and staircase are synonyms defined as:

stairway and staircase: a way of access (upward and downward) consisting of a set of steps

stairway (noun)	staircase (noun)
a way of access (upward and downward) consisting of a set of steps	a way of access (upward and downward) consisting of a set of steps