atmosphere vs sky

atmosphere and sky both are nouns.

Word	Noun	Adjective	Verb	Adverb
atmosphere	Yes	No	No	No
sky	Yes	No	Yes	No

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

atmosphere (noun)	sky (noun)
a distinctive but intangible quality surrounding a person or thing	the atmosphere and outer space as viewed from the earth
the mass of air surrounding the Earth
the envelope of gases surrounding any celestial body
a unit of pressure: the pressure that will support a column of mercury 760 mm high at sea level and 0 degrees centigrade
the weather or climate at some place
a particular environment or surrounding influence

atmosphere (verb)	sky (verb)
	throw or toss with a light motion