There are two address versions, one that has mixed-case letters and one that does not. See the examples below:
Both of these addresses are exactly the same, except for the uppercase and the lowercase letters. Capitalization simply means that the address has a built-in checksum. Both represent the same account and are equally valid for all transactions.
COBINHOOD uses checksums to prevent users from mistyping addresses. If an address is keyed in incorrectly, the checksum mechanism will warn the user that it's invalid. Checksums are much safer for user.