horizon vs apparent horizon

horizon and apparent horizon both are nouns.

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

As nouns, horizon and apparent horizon are synonyms defined as:

horizon and apparent horizon: the line at which the sky and Earth appear to meet

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

horizon (noun)	apparent horizon (noun)
the range of interest or activity that can be anticipated	the line at which the sky and Earth appear to meet
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