natural philosophy vs gravitational theory

natural philosophy and gravitational theory both are nouns.

Word	Noun	Adjective	Verb	Adverb
natural philosophy	Yes	No	No	No
gravitational theory	Yes	No	No	No

natural philosophy (noun)	gravitational theory (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