fiberglass vs fibreglass

fiberglass and fibreglass both are nouns.

Word	Noun	Adjective	Verb	Adverb
fiberglass	Yes	No	No	No
fibreglass	Yes	No	No	No

As nouns, fiberglass and fibreglass are synonyms defined as:

fiberglass and fibreglass: a covering material made of glass fibers in resins

fiberglass (noun)	fibreglass (noun)
a covering material made of glass fibers in resins	a covering material made of glass fibers in resins