star vs matinee idol

star and matinee idol both are nouns.

Word	Noun	Adjective	Verb	Adverb
star	Yes	Yes	Yes	No
matinee idol	Yes	No	No	No

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

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

star (noun)	matinee idol (noun)
the topology of a network whose components are connected to a hub	someone who is adored blindly and excessively
a star-shaped character * used in printing
(astronomy) a celestial body of hot gases that radiates energy derived from thermonuclear reactions in the interior
any celestial body visible (as a point of light) from the Earth at night
an actor who plays a principal role
someone who is dazzlingly skilled in any field
a performer who receives prominent billing
a plane figure with 5 or more points; often used as an emblem

star (adjective)	matinee idol (adjective)
indicating the most important performer or role