zillion vs trillion

zillion and trillion both are nouns.

Word	Noun	Adjective	Verb	Adverb
zillion	Yes	Yes	No	No
trillion	Yes	Yes	No	No

As nouns, zillion and trillion are synonyms defined as:

zillion and trillion: a very large indefinite number (usually hyperbole)

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

zillion (noun)	trillion (noun)
a very large indefinite number (usually hyperbole)	the number that is represented as a one followed by 12 zeros
	the number that is represented as a one followed by 18 zeros in the UK
	a very large indefinite number (usually hyperbole)

zillion (adjective)	trillion (adjective)
very large indeterminate number	one million million in the United States
	one quintillion in Great Britain