blank check vs blank cheque

blank check and blank cheque both are nouns.

Word	Noun	Adjective	Verb	Adverb
blank check	Yes	No	No	No
blank cheque	Yes	No	No	No

As nouns, blank check and blank cheque are synonyms defined as:

blank check and blank cheque: a check that has been signed but with the amount payable left blank

blank check (noun)	blank cheque (noun)
a check that has been signed but with the amount payable left blank	a check that has been signed but with the amount payable left blank
freedom to do as you see fit