biological defence vs biological defense

biological defence and biological defense both are nouns.

Word	Noun	Adjective	Verb	Adverb
biological defence	Yes	No	No	No
biological defense	Yes	No	No	No

As nouns, biological defence and biological defense are synonyms defined as:

biological defence and biological defense: procedures involved in taking defensive measures against attacks using biological agents

Other synonyms of biological defence include biodefence, biodefense.

biological defence (noun)	biological defense (noun)
procedures involved in taking defensive measures against attacks using biological agents	procedures involved in taking defensive measures against attacks using biological agents