diction vs choice of words

diction and choice of words both are nouns.

Word	Noun	Adjective	Verb	Adverb
diction	Yes	No	No	No
choice of words	Yes	No	No	No

As nouns, diction and choice of words are synonyms defined as:

diction and choice of words: the manner in which something is expressed in words

Other synonyms of diction include phraseology, phrasing, verbiage, wording.

diction (noun)	choice of words (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