protoheme vs haemoglobin

protoheme and haemoglobin both are nouns.

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

protoheme (noun)	haemoglobin (noun)
a complex red organic pigment containing iron and other atoms to which oxygen binds	a hemoprotein composed of globin and heme that gives red blood cells their characteristic color; function primarily to transport oxygen from the lungs to the body tissues