indirect tax vs taxation

indirect tax and taxation both are nouns.

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

As nouns, taxation is a hypernym of indirect tax; that is, taxation is a word with a broader meaning than indirect tax:

indirect tax: a tax levied on goods or services rather than on persons or organizations
taxation: charge against a citizen's person or property or activity for the support of government

Other hypernyms of indirect tax include revenue enhancement, tax.

indirect tax (noun)	taxation (noun)
a tax levied on goods or services rather than on persons or organizations	the imposition of taxes; the practice of the government in levying taxes on the subjects of a state
	charge against a citizen's person or property or activity for the support of government
	government income due to taxation