estriol vs oestriol

estriol and oestriol both are nouns.

Word	Noun	Adjective	Verb	Adverb
estriol	Yes	No	No	No
oestriol	Yes	No	No	No

As nouns, estriol and oestriol are synonyms defined as:

estriol and oestriol: a naturally occurring estrogenic hormone; a synthetic form is used to treat estrogen deficiency

estriol (noun)	oestriol (noun)
a naturally occurring estrogenic hormone; a synthetic form is used to treat estrogen deficiency	a naturally occurring estrogenic hormone; a synthetic form is used to treat estrogen deficiency