menstruation vs menses

menstruation and menses both are nouns.

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

As nouns, menstruation and menses are synonyms defined as:

menstruation and menses: the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause

Other synonyms of menstruation include catamenia, flow, menstruum, period.

menstruation (noun)	menses (noun)
the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause	the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause