berry vs saskatoon

berry and saskatoon both are nouns.

Word	Noun	Adjective	Verb	Adverb
berry	Yes	No	Yes	No
saskatoon	Yes	No	No	No

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

berry: any of numerous small and pulpy edible fruits; used as desserts or in making jams and jellies and preserves
saskatoon: edible purple or red berries

berry (noun)	saskatoon (noun)
any of numerous small and pulpy edible fruits; used as desserts or in making jams and jellies and preserves	edible purple or red berries
a small fruit having any of various structures, e.g., simple (grape or blueberry) or aggregate (blackberry or raspberry)

berry (verb)	saskatoon (verb)
pick or gather berries