circularisation vs circularization

circularisation and circularization both are nouns.

Word	Noun	Adjective	Verb	Adverb
circularisation	Yes	No	No	No
circularization	Yes	No	No	No

As nouns, circularisation and circularization are synonyms defined as:

circularisation and circularization: circulating printed notices as a means of advertising

circularisation (noun)	circularization (noun)
circulating printed notices as a means of advertising	circulating printed notices as a means of advertising