ritual vs espousal

ritual and espousal both are nouns.

Word	Noun	Adjective	Verb	Adverb
ritual	Yes	Yes	No	No
espousal	Yes	No	No	No

As nouns, espousal is a hyponym of ritual; that is, espousal is a word with a more specific, narrower meaning than ritual:

Other hyponyms of ritual include betrothal, marriage, marriage ceremony, wedding, rite of passage.

ritual (noun)	espousal (noun)
any customary observance or practice	the act of accepting with approval; favorable reception
the prescribed procedure for conducting religious ceremonies	archaic terms for a wedding or wedding feast
stereotyped behavior	the act of becoming betrothed or engaged

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