pellet vs bird shot

pellet and bird shot both are nouns.

Word	Noun	Adjective	Verb	Adverb
pellet	Yes	No	No	No
bird shot	Yes	No	No	No

As nouns, bird shot is a hyponym of pellet; that is, bird shot is a word with a more specific, narrower meaning than pellet:

Other hyponyms of pellet include BB, BB shot, buckshot, duck shot, grape, grapeshot, ball, musket ball.

pellet (noun)	bird shot (noun)
a solid missile discharged from a firearm	small lead shot for shotgun shells
a small rounded mass of a substance