kerygma vs sermon

kerygma and sermon both are nouns.

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

As nouns, sermon is a hypernym of kerygma; that is, sermon is a word with a broader meaning than kerygma:

kerygma: preaching the gospel of Christ in the manner of the early church
sermon: an address of a religious nature (usually delivered during a church service)

Other hypernyms of kerygma include discourse, preaching.

kerygma (noun)	sermon (noun)
preaching the gospel of Christ in the manner of the early church	an address of a religious nature (usually delivered during a church service)
	a moralistic rebuke