skyline vs horizon

skyline and horizon both are nouns.

Word	Noun	Adjective	Verb	Adverb
skyline	Yes	No	No	No
horizon	Yes	No	No	No

As nouns, skyline and horizon are synonyms defined as:

Other synonyms of skyline include apparent horizon, sensible horizon, visible horizon.

skyline (noun)	horizon (noun)
the line at which the sky and Earth appear to meet	the range of interest or activity that can be anticipated
the outline of objects seen against the sky	the line at which the sky and Earth appear to meet
	a specific layer or stratum of soil or subsoil in a vertical cross section of land
	the great circle on the celestial sphere whose plane passes through the sensible horizon and the center of the Earth