estrogen vs oestrogen

estrogen and oestrogen both are nouns.

Word	Noun	Adjective	Verb	Adverb
estrogen	Yes	No	No	No
oestrogen	Yes	No	No	No

As nouns, estrogen and oestrogen are synonyms defined as:

estrogen and oestrogen: a general term for female steroid sex hormones that are secreted by the ovary and responsible for typical female sexual characteristics

estrogen (noun)	oestrogen (noun)
a general term for female steroid sex hormones that are secreted by the ovary and responsible for typical female sexual characteristics	a general term for female steroid sex hormones that are secreted by the ovary and responsible for typical female sexual characteristics