working party vs working group

working party and working group both are nouns.

Word	Noun	Adjective	Verb	Adverb
working party	Yes	No	No	No
working group	Yes	No	No	No

As nouns, working party and working group are synonyms defined as:

working party and working group: a group of people working together temporarily until some goal is achieved

working party (noun)	working group (noun)
a group of people working together temporarily until some goal is achieved	a group of people working together temporarily until some goal is achieved