tax bracket vs income tax bracket

tax bracket and income tax bracket both are nouns.

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

As nouns, tax bracket and income tax bracket are synonyms defined as:

tax bracket and income tax bracket: a category of taxpayers based on the amount of their income

Other synonyms of tax bracket include income bracket.

tax bracket (noun)	income tax bracket (noun)
a category of taxpayers based on the amount of their income	a category of taxpayers based on the amount of their income