officialese vs expressive style

officialese and expressive style both are nouns.

Word	Noun	Adjective	Verb	Adverb
officialese	Yes	No	No	No
expressive style	Yes	No	No	No

As nouns, expressive style is a hypernym of officialese; that is, expressive style is a word with a broader meaning than officialese:

officialese: the style of writing characteristic of some government officials: formal and obscure
expressive style: a way of expressing something (in language or art or music etc.) that is characteristic of a particular person or group of people or period

Other hypernyms of officialese include style.

officialese (noun)	expressive style (noun)
the style of writing characteristic of some government officials: formal and obscure	a way of expressing something (in language or art or music etc.) that is characteristic of a particular person or group of people or period