working papers vs work permit

working papers and work permit both are nouns.

Word	Noun	Adjective	Verb	Adverb
working papers	Yes	No	No	No
work permit	Yes	No	No	No

As nouns, working papers and work permit are synonyms defined as:

working papers and work permit: a legal document giving information required for employment of certain people in certain countries

Other synonyms of working papers include work papers.

working papers (noun)	work permit (noun)
a legal document giving information required for employment of certain people in certain countries	a legal document giving information required for employment of certain people in certain countries
records kept of activities involved in carrying out a project