principle of relativity vs natural philosophy

principle of relativity and natural philosophy both are nouns.

Word	Noun	Adjective	Verb	Adverb
principle of relativity	Yes	No	No	No
natural philosophy	Yes	No	No	No

principle of relativity (noun)	natural philosophy (noun)
(physics) a universal law that states that the laws of mechanics are not affected by a uniform rectilinear motion of the system of coordinates to which they are referred	the science of matter and energy and their interactions