natural philosophy vs theory of gravitation

natural philosophy and theory of gravitation both are nouns.

Word	Noun	Adjective	Verb	Adverb
natural philosophy	Yes	No	No	No
theory of gravitation	Yes	No	No	No

natural philosophy (noun)	theory of gravitation (noun)
the science of matter and energy and their interactions	(physics) the theory that any two particles of matter attract one another with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them