haemitin vs protoheme

haemitin and protoheme both are nouns.

Word	Noun	Adjective	Verb	Adverb
haemitin	Yes	No	No	No
protoheme	Yes	No	No	No

As nouns, haemitin and protoheme are synonyms defined as:

haemitin and protoheme: a complex red organic pigment containing iron and other atoms to which oxygen binds

Other synonyms of haemitin include haem, hematin, heme.

haemitin (noun)	protoheme (noun)
a complex red organic pigment containing iron and other atoms to which oxygen binds	a complex red organic pigment containing iron and other atoms to which oxygen binds