occurrence vs allopatry

occurrence and allopatry both are nouns.

Word	Noun	Adjective	Verb	Adverb
occurrence	Yes	No	No	No
allopatry	Yes	No	No	No

As nouns, allopatry is a hyponym of occurrence; that is, allopatry is a word with a more specific, narrower meaning than occurrence:

occurrence: an instance of something occurring
allopatry: the occurrence of related organisms in separate geographical areas with no overlap

Other hyponyms of occurrence include sympatry.

occurrence (noun)	allopatry (noun)
an event that happens	the occurrence of related organisms in separate geographical areas with no overlap
an instance of something occurring