Comment
First one looks original and very good, but doesn't say what bike it is from, so if it looks good and you know what it fits, go for it. Pic is clear enough to count the teeth on the gear... 
Second part # looks like a common repro, you may be able to shop around and find cheaper, not need to jump on it as they are listed all the time.
email (option): vinver@ns.sympatico.ca