carotene vs carotin

carotene and carotin both are nouns.

Word	Noun	Adjective	Verb	Adverb
carotene	Yes	No	No	No
carotin	Yes	No	No	No

As nouns, carotene and carotin are synonyms defined as:

carotene and carotin: an orange isomer of an unsaturated hydrocarbon found in many plants; is converted into vitamin A in the liver

Other synonyms of carotene include provitamin A.

carotene (noun)	carotin (noun)
an orange isomer of an unsaturated hydrocarbon found in many plants; is converted into vitamin A in the liver	an orange isomer of an unsaturated hydrocarbon found in many plants; is converted into vitamin A in the liver
yellow or orange-red fat-soluble pigments in plants