stairs vs steps

stairs and steps both are nouns.

Word	Noun	Adjective	Verb	Adverb
stairs	Yes	No	No	No
steps	Yes	No	No	No

As nouns, stairs and steps are synonyms defined as:

stairs (noun)	steps (noun)
a flight of stairs or a flight of steps	a flight of stairs or a flight of steps
	the course along which a person has walked or is walking in