test paper vs indicator

test paper and indicator both are nouns.

Word	Noun	Adjective	Verb	Adverb
test paper	Yes	No	No	No
indicator	Yes	No	No	No

As nouns, indicator is a hypernym of test paper; that is, indicator is a word with a broader meaning than test paper:

test paper (noun)	indicator (noun)
paper impregnated with an indicator for use in chemical tests	a device for showing the operating condition of some system
a written examination	a number or ratio (a value on a scale of measurement) derived from a series of observed facts; can reveal relative changes as a function of time
	a signal for attracting attention
	(chemistry) a substance that changes color to indicate the presence of some ion or substance; can be used to indicate the completion of a chemical reaction or (in medicine) to test for a particular reaction