self-fertilisation vs self-fertilization

self-fertilisation and self-fertilization both are nouns.

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

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

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

self-fertilisation (noun)	self-fertilization (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