menorrhagia vs menstruation

menorrhagia and menstruation both are nouns.

Word	Noun	Adjective	Verb	Adverb
menorrhagia	Yes	No	No	No
menstruation	Yes	No	No	No

As nouns, menstruation is a hypernym of menorrhagia; that is, menstruation is a word with a broader meaning than menorrhagia:

menorrhagia: abnormally heavy or prolonged menstruation; can be a symptom of uterine tumors and can lead to anemia if prolonged
menstruation: the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause

Other hypernyms of menorrhagia include catamenia, flow, menses, menstruum, period, symptom.

menorrhagia (noun)	menstruation (noun)
abnormally heavy or prolonged menstruation; can be a symptom of uterine tumors and can lead to anemia if prolonged	the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause