thing vs occurrence

thing and occurrence both are nouns.

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

As nouns, occurrence is a hypernym of thing; that is, occurrence is a word with a broader meaning than thing:

Other hypernyms of thing include happening, natural event, occurrent.

thing (noun)	occurrence (noun)
a separate and self-contained entity	an event that happens
an action	an instance of something occurring
an artifact
an entity that is not named specifically
any attribute or quality considered as having its own existence
a special abstraction
a special objective
a vaguely specified concern
a statement regarded as an object
an event
a persistent illogical feeling of desire or aversion
a special situation