platform vs horizontal surface

platform and horizontal surface both are nouns.

Word	Noun	Adjective	Verb	Adverb
platform	Yes	No	No	No
horizontal surface	Yes	No	No	No

As nouns, horizontal surface is a hypernym of platform; that is, horizontal surface is a word with a broader meaning than platform:

Other hypernyms of platform include level.

platform (noun)	horizontal surface (noun)
a raised horizontal surface	a flat surface at right angles to a plumb line
any military structure or vehicle bearing weapons
a woman's shoe with a very high thick sole
the combination of a particular computer and a particular operating system
a long, flat raised structure of a railway station, where people get on and off of trains
a document stating the aims and principles of a political party