discourse vs dilation

discourse and dilation both are nouns.

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

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

discourse: an extended communication (often interactive) dealing with some particular topic
dilation: a lengthy discussion (spoken or written) on a particular topic

Other hyponyms of discourse include detail, consideration, talk, elaboration, enlargement, expansion.

discourse (noun)	dilation (noun)
an extended communication (often interactive) dealing with some particular topic	the act of expanding an aperture
extended verbal expression in speech or writing	a lengthy discussion (spoken or written) on a particular topic
an address of a religious nature (usually delivered during a church service)

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