marriage ceremony vs ritual

marriage ceremony and ritual both are nouns.

Word	Noun	Adjective	Verb	Adverb
marriage ceremony	Yes	No	No	No
ritual	Yes	Yes	No	No

As nouns, ritual is a hypernym of marriage ceremony; that is, ritual is a word with a broader meaning than marriage ceremony:

Other hypernyms of marriage ceremony include rite.

marriage ceremony (noun)	ritual (noun)
the act of marrying; the nuptial ceremony	any customary observance or practice
	the prescribed procedure for conducting religious ceremonies
	stereotyped behavior

marriage ceremony (adjective)	ritual (adjective)
	of or relating to or employed in social rites or rituals
	of or relating to or characteristic of religious rituals