sermon vs evangelism

sermon and evangelism both are nouns.

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

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

sermon: an address of a religious nature (usually delivered during a church service)
evangelism: zealous preaching and advocacy of the gospel

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

sermon (noun)	evangelism (noun)
an address of a religious nature (usually delivered during a church service)	zealous preaching and advocacy of the gospel
a moralistic rebuke