meeting vs appointment

meeting and appointment both are nouns.

Word	Noun	Adjective	Verb	Adverb
meeting	Yes	No	No	No
appointment	Yes	No	No	No

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

meeting (noun)	appointment (noun)
the social act of assembling for some common purpose	the act of putting a person into a non-elective position
the act of joining together as one	the job to which you are (or hope to be) appointed
a casual or unexpected convergence	(law) the act of disposing of property by virtue of the power of appointment
a formally arranged gathering	(usually in the plural) furnishings and equipment (especially for a ship or hotel)
a small informal social gathering	a meeting arranged in advance
a place where things merge or flow together (especially rivers)	a person who is appointed to a job or position