function vs occasion

function and occasion both are nouns.

Word	Noun	Adjective	Verb	Adverb
function	Yes	No	Yes	No
occasion	Yes	No	Yes	No

As nouns, function and occasion are synonyms defined as:

function and occasion: a formal or official social gathering or ceremony of people

Other synonyms of function include affair, social affair, social function, social gathering, social occasion.

As nouns, occasion is a hypernym of function; that is, occasion is a word with a broader meaning than function:

Other hypernyms of function include affair, function, social affair, social function, social gathering, social occasion.

function (noun)	occasion (noun)
the actions and activities assigned to or required or expected of a person or group	an event that occurs at a critical time
what something is used for	a formal or official social gathering or ceremony of people
a set sequence of steps, part of larger computer program	a rational motive for a belief or action
a formal or official social gathering or ceremony of people	an opportunity to do something
a formal or official social gathering or ceremony	the time of a particular event
(mathematics) a mathematical relation such that each element of a given set (the domain of the function) is associated with an element of another set (the range of the function)
a relation such that one thing is dependent on another

function (verb)	occasion (verb)
perform duties attached to a particular office or place or function	give occasion to
perform as expected when applied
serve a purpose, role, or function