million vs gazillion

million and gazillion both are nouns.

Word	Noun	Adjective	Verb	Adverb
million	Yes	Yes	No	No
gazillion	Yes	No	No	No

As nouns, million and gazillion are synonyms defined as:

million and gazillion: a very large indefinite number (usually hyperbole)

Other synonyms of million include bazillion, billion, jillion, trillion, zillion.

million (noun)	gazillion (noun)
the number that is represented as a one followed by 6 zeros	a very large indefinite number (usually hyperbole)
a very large indefinite number (usually hyperbole)

million (adjective)	gazillion (adjective)
(in Roman numerals, M written with a macron over it) denoting a quantity consisting of 1,000,000 items or units