hold forth vs discourse

hold forth is not a noun while discourse is a noun.

Word	Noun	Adjective	Verb	Adverb
hold forth	No	No	Yes	No
discourse	Yes	No	Yes	No

As verbs, hold forth and discourse are synonyms defined as:

Other synonyms of hold forth include dissertate.

hold forth (noun)	discourse (noun)
	an extended communication (often interactive) dealing with some particular topic
	extended verbal expression in speech or writing
	an address of a religious nature (usually delivered during a church service)

hold forth (verb)	discourse (verb)
talk at length and formally about a topic	talk at length and formally about a topic
	carry on a conversation
	to consider or examine in speech or writing