GM originally made these keys with the big keyring hole. After the ingition recall on many models, they redesigned the key with a smaller keyring hole. Originally these keys were made with the different logos for all the GM brands (Buick, Cadillac, etc...) but since the redesign, the only logo made is the GM logo.
Have a local locksmith cut the key to work your vehicle. If you have an existing key to copy, cutting will be very inexpensive.