taxation vs income tax

taxation and income tax both are nouns.

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

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

taxation: charge against a citizen's person or property or activity for the support of government
income tax: a personal tax levied on annual income

taxation (noun)	income tax (noun)
the imposition of taxes; the practice of the government in levying taxes on the subjects of a state	a personal tax levied on annual income
charge against a citizen's person or property or activity for the support of government
government income due to taxation