"the deliberate killing of a large group of people, especially those of a particular ethnic group or nation."
While xenocide is described as:
xenocide (plural xenocides)
The killing of a stranger or foreigner. (science fiction) The genocide of an entire alien species. (US, colloquial) The intentional killing of an entire foreign (plant or animal) species.
https://en.wiktionary.org/wiki/xenocide
Either is fine really, just seems like a semantic curiosity.