formality vs ceremony

formality and ceremony both are nouns.

Word	Noun	Adjective	Verb	Adverb
formality	Yes	No	No	No
ceremony	Yes	No	No	No

As nouns, ceremony is a hypernym of formality; that is, ceremony is a word with a broader meaning than formality:

Other hypernyms of formality include ceremonial, ceremonial occasion, observance.

formality (noun)	ceremony (noun)
compliance with formal rules	the proper or conventional behavior on some solemn occasion
a manner that strictly observes all forms and ceremonies	any activity that is performed in an especially solemn elaborate or formal way
a requirement of etiquette or custom	a formal event performed on a special occasion