knoll vs koppie

knoll and koppie both are nouns.

Word	Noun	Adjective	Verb	Adverb
knoll	Yes	No	No	No
koppie	Yes	No	No	No

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

Other hyponyms of knoll include anthill, formicary, kopje, molehill.

knoll (noun)	koppie (noun)
a small natural hill	a small hill rising up from the African veld