uranologist vs Claudius Ptolemaeus

uranologist and Claudius Ptolemaeus both are nouns.

Word	Noun	Adjective	Verb	Adverb
uranologist	Yes	No	No	No
Claudius Ptolemaeus	Yes	No	No	No

uranologist (noun)	Claudius Ptolemaeus (noun)
a physicist who studies astronomy	Alexandrian astronomer (of the 2nd century) who proposed a geocentric system of astronomy that was undisputed until the late Renaissance