sago vs pearl sago

sago and pearl sago both are nouns.

Word	Noun	Adjective	Verb	Adverb
sago	Yes	No	No	No
pearl sago	Yes	No	No	No

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

sago: powdery starch from certain sago palms; used in Asia as a food thickener and textile stiffener
pearl sago: sago ground into small round grains

sago (noun)	pearl sago (noun)
powdery starch from certain sago palms; used in Asia as a food thickener and textile stiffener	sago ground into small round grains