organise vs get together

organise is not a noun while get together is a noun.

Word	Noun	Adjective	Verb	Adverb
organise	No	No	Yes	No
get together	Yes	No	Yes	No

As verbs, get together is a hypernym of organise; that is, get together is a word with a broader meaning than organise:

Other hypernyms of organise include fall in, join.

organise (noun)	get together (noun)
	a small informal social gathering

organise (verb)	get together (verb)
bring order and organization to	get together socially or for a specific purpose
plan and direct (a complex undertaking)	become part of; become a member of a group or organization
arrange by systematic planning and united effort	get people together
cause to be structured or ordered or operating according to some principle or idea
create (as an entity)
form or join a union