They are essentially the same as condominiums. Here is how it works:
Condo- This is really a form of ownership and has nothing to do with the actual building (Could be a detached house in a nieghborhood or a multi-unit building) With a condo you own the airspace inside the structure the condominium association ownes the structure and common areas. Your condo association fees fund maintenance and other expenses.
Co-op- You own a share of stock that entitles you to live in a unit of the cooperative real estate. You will probably also have to pay an association fee.
The benefits of co ops, like condos, are you will not have the added responsibility of keeping up the exterior, the grounds, or other common areas. Association fees take care of that. Check with a local agent or attorney. My expertise is in the Fayetteville NC real estate market and local customs and laws vary.