flower vs heyday

flower and heyday both are nouns.

Word	Noun	Adjective	Verb	Adverb
flower	Yes	No	Yes	No
heyday	Yes	No	No	No

As nouns, flower and heyday are synonyms defined as:

Other synonyms of flower include bloom, blossom, efflorescence, flush, peak, prime.

flower (noun)	heyday (noun)
a plant cultivated for its blooms or blossoms	the period of greatest prosperity or productivity
reproductive organ of angiosperm plants especially one having showy or colorful parts
the period of greatest prosperity or productivity

flower (verb)	heyday (verb)
produce or yield flowers