penny vs new penny

penny and new penny both are nouns.

Word	Noun	Adjective	Verb	Adverb
penny	Yes	No	No	No
new penny	Yes	No	No	No

As nouns, new penny is a hyponym of penny; that is, new penny is a word with a more specific, narrower meaning than penny:

penny: a coin worth one-hundredth of the value of the basic unit
new penny: a coin used in Great Britain since 1971 worth one hundredth of a pound

Other hyponyms of penny include copper.

penny (noun)	new penny (noun)
a coin worth one-hundredth of the value of the basic unit	a coin used in Great Britain since 1971 worth one hundredth of a pound
a fractional monetary unit of Ireland and the United Kingdom; equal to one hundredth of a pound