mouthful vs morsel

mouthful and morsel both are nouns.

Word	Noun	Adjective	Verb	Adverb
mouthful	Yes	No	No	No
morsel	Yes	No	No	No

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

Other hyponyms of mouthful include bit, bite, sup, swallow.

mouthful (noun)	morsel (noun)
a small amount eaten or drunk	a small amount of solid food; a mouthful
the quantity that can be held in the mouth	a small quantity of anything