You need at least 500 reputation to review Close Votes.
Which one is the right one ?
They both are correct. While you only need 250 reputation to view close votes (i.e. see how many close votes have been cast on a question), you still need 500 reputation to actually cast close votes.
One of the requirements of going through the Close Votes review queue is figuring out whether you need to add your own close vote into the mix; as such, the larger 500 reputation requirement to cast a vote is the minimum for review.