pillar of Islam vs Mohammedanism

pillar of Islam and Mohammedanism both are nouns.

Word	Noun	Adjective	Verb	Adverb
pillar of Islam	Yes	No	No	No
Mohammedanism	Yes	No	No	No

pillar of Islam (noun)	Mohammedanism (noun)
(Islam) one of the five religious obligations accepted by all Muslims	the monotheistic religious system of Muslims founded in Arabia in the 7th century and based on the teachings of Muhammad as laid down in the Koran