sermon vs homily

sermon and homily both are nouns.

Word	Noun	Adjective	Verb	Adverb
sermon	Yes	No	No	No
homily	Yes	No	No	No

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

sermon: an address of a religious nature (usually delivered during a church service)
homily: a sermon on a moral or religious topic

Other hyponyms of sermon include baccalaureate, kerugma, kerygma, evangelism, preachment.

sermon (noun)	homily (noun)
an address of a religious nature (usually delivered during a church service)	a sermon on a moral or religious topic
a moralistic rebuke