tax return vs legal instrument

tax return and legal instrument both are nouns.

Word	Noun	Adjective	Verb	Adverb
tax return	Yes	No	No	No
legal instrument	Yes	No	No	No

As nouns, legal instrument is a hypernym of tax return; that is, legal instrument is a word with a broader meaning than tax return:

tax return: document giving the tax collector information about the taxpayer's tax liability
legal instrument: (law) a document that states some contractual relationship or grants some right

Other hypernyms of tax return include instrument, legal document, official document.

tax return (noun)	legal instrument (noun)
document giving the tax collector information about the taxpayer's tax liability	(law) a document that states some contractual relationship or grants some right