past perfect tense vs pluperfect

past perfect tense and pluperfect both are nouns.

Word	Noun	Adjective	Verb	Adverb
past perfect tense	Yes	No	No	No
pluperfect	Yes	Yes	No	No

As nouns, past perfect tense and pluperfect are synonyms defined as:

past perfect tense and pluperfect: a perfective tense used to express action completed in the past

Other synonyms of past perfect tense include past perfect, pluperfect tense.

past perfect tense (noun)	pluperfect (noun)
a perfective tense used to express action completed in the past	a perfective tense used to express action completed in the past

past perfect tense (adjective)	pluperfect (adjective)
	more than perfect