cotton wool vs cotton fiber

cotton wool and cotton fiber both are nouns.

Word	Noun	Adjective	Verb	Adverb
cotton wool	Yes	No	No	No
cotton fiber	Yes	No	No	No

As nouns, cotton wool and cotton fiber are synonyms defined as:

cotton wool and cotton fiber: soft silky fibers from cotton plants in their raw state

Other synonyms of cotton wool include cotton.

cotton wool (noun)	cotton fiber (noun)
soft silky fibers from cotton plants in their raw state	soft silky fibers from cotton plants in their raw state