principal vs idol

principal and idol both are nouns.

Word	Noun	Adjective	Verb	Adverb
principal	Yes	Yes	No	No
idol	Yes	No	No	No

As nouns, idol is a hyponym of principal; that is, idol is a word with a more specific, narrower meaning than principal:

Other hyponyms of principal include co-star, film star, movie star, matinee idol, television star, TV star.

principal (noun)	idol (noun)
the educator who has executive authority for a school	a material effigy that is worshipped
an actor who plays a principal role	an ideal instance; a perfect embodiment of a concept
the major party to a financial transaction at a stock exchange; buys and sells for his own account	someone who is adored blindly and excessively
(criminal law) any person involved in a criminal offense, regardless of whether the person profits from such involvement
the original amount of a debt on which interest is calculated
capital as contrasted with the income derived from it

principal (adjective)	idol (adjective)
most important element