discourse vs speak

discourse is a noun but speak is not a noun.

Word	Noun	Adjective	Verb	Adverb
discourse	Yes	No	Yes	No
speak	No	No	Yes	No

As verbs, speak is a hypernym of discourse; that is, speak is a word with a broader meaning than discourse:

Other hypernyms of discourse include talk.

As verbs, speak is a hypernym of discourse; that is, speak is a word with a broader meaning than discourse:

Other hypernyms of discourse include talk.

discourse (noun)	speak (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)

discourse (verb)	speak (verb)
talk at length and formally about a topic	express in speech
carry on a conversation	exchange thoughts; talk with
to consider or examine in speech or writing	use language
	give a speech to
	make a characteristic or natural sound