self-fertilization vs self-fertilisation

self-fertilization and self-fertilisation both are nouns.

Word	Noun	Adjective	Verb	Adverb
self-fertilization	Yes	No	No	No
self-fertilisation	Yes	No	No	No

As nouns, self-fertilization and self-fertilisation are synonyms defined as:

self-fertilization and self-fertilisation: fertilization by the union of male and female gametes from the same individual

self-fertilization (noun)	self-fertilisation (noun)
fertilization by the union of male and female gametes from the same individual	fertilization by the union of male and female gametes from the same individual