red ink vs paper loss

red ink and paper loss both are nouns.

Word	Noun	Adjective	Verb	Adverb
red ink	Yes	No	No	No
paper loss	Yes	No	No	No

As nouns, paper loss is a hyponym of red ink; that is, paper loss is a word with a more specific, narrower meaning than red ink:

red ink: the amount by which the cost of a business exceeds its revenue
paper loss: an unrealized loss on an investment calculated by subtracting the current market price from the investor's cost

Other hyponyms of red ink include squeeze.

red ink (noun)	paper loss (noun)
the amount by which the cost of a business exceeds its revenue	an unrealized loss on an investment calculated by subtracting the current market price from the investor's cost