occurrence vs sympatry

occurrence and sympatry both are nouns.

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

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

occurrence: an instance of something occurring
sympatry: the occurrence of organisms in overlapping geographical areas, but without interbreeding

Other hyponyms of occurrence include allopatry.

occurrence (noun)	sympatry (noun)
an event that happens	the occurrence of organisms in overlapping geographical areas, but without interbreeding
an instance of something occurring