original sin vs sin

original sin and sin both are nouns.

Word	Noun	Adjective	Verb	Adverb
original sin	Yes	No	No	No
sin	Yes	No	Yes	No

As nouns, sin is a hypernym of original sin; that is, sin is a word with a broader meaning than original sin:

original sin: a sin said to be inherited by all descendants of Adam
sin: an act that is regarded by theologians as a transgression of God's will

Other hypernyms of original sin include sinning, church doctrine, creed, gospel, religious doctrine.

original sin (noun)	sin (noun)
a sin said to be inherited by all descendants of Adam	an act that is regarded by theologians as a transgression of God's will
	estrangement from god
	the 21st letter of the Hebrew alphabet
	ratio of the length of the side opposite the given angle to the length of the hypotenuse of a right-angled triangle

original sin (verb)	sin (verb)
	commit a sin; violate a law of God or a moral law
	commit a faux pas or a fault or make a serious mistake