phraseology vs diction

phraseology and diction both are nouns.

Word	Noun	Adjective	Verb	Adverb
phraseology	Yes	No	No	No
diction	Yes	No	No	No

As nouns, phraseology and diction are synonyms defined as:

phraseology and diction: the manner in which something is expressed in words

Other synonyms of phraseology include choice of words, phrasing, verbiage, wording.

phraseology (noun)	diction (noun)
the manner in which something is expressed in words	the manner in which something is expressed in words
	the articulation of speech regarded from the point of view of its intelligibility to the audience