bracket vs tax bracket

bracket and tax bracket both are nouns.

Word	Noun	Adjective	Verb	Adverb
bracket	Yes	No	Yes	No
tax bracket	Yes	No	No	No

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

Other hyponyms of bracket include income bracket, income tax bracket, price bracket.

bracket (noun)	tax bracket (noun)
a support projecting from a wall (as to hold a shelf)	a category of taxpayers based on the amount of their income
either of two punctuation marks ([ or ]) used to enclose textual material
either of two punctuation marks (`<' or `>') used in computer programming and sometimes used to enclose textual material
a category falling within certain defined limits