These are forms of ownership. With a condo you own from the inside walls in and a common interest in the exterior grounds and buildings. With a coop you own an undivided interest in the building and grounds which is represented as shares of stock. You do not own your individual unit, you receive a lease for the unit from the association. As a result the closing process and financing will also be different.
The coop board functions as the landlord and often has the right to deny a lease to anyone they deem undesirable. This can sometimes make selling your coop difficult and could limit your buyer pool.
Personally we would prefer a condo as it provides a little more freedom to you in managing your property.
Hope this helps.
The advantages to owning a condo are that the condo is yours, buying a condo is like buying a house, you can finance a condo just as you would a house, and you can sell when you want and to whom you want. You are subject to the rules set up by the condo association, and to paying condo fees to cover costs for the common areas of the property plus any included utilities and services.
When you buy shares of stock in a coop you are not techincally buying real estate. The coop board can determine who they will allow to buy into the coop and who they will not. In Philadelphia you cannot get a mortgage to buy a coop. You will have to demonstrate to the coop association that you have sufficient assets to be able to pay the monthly coop fees, which are generally about the same as condo fees. Coops in Philadelphia generally sell for much less than a comparable condo.
The coop arrangement can be very beneficial for people who have the cash to buy, are not thinking of gaining equity or being able to sell quickly, and who are happy to be part of the coop community. Otherwise the condo is the better choice.