A condominium building is typically comprised of individual apartments and common areas. When you purchase a condo unit, you own the apartment as well as a joint ownership in the common areas with your fellow residents. You’re responsible for your own real estate taxes and you share expense charges to maintain and operate the common areas of the building.
Unlike a condo unit, a co-op is owned by a corporation, which owns the apartment building. By purchasing a co-op unit, you aren’t buying real property, instead you’re buying shares of stock in the corporation itself. Buying shares then allows you to sign a proprietary lease with the building for an individual apartment. Typically, the more shares you purchase, the larger the apartment. You’re responsible for paying monthly maintenance to the building corporation for items including property taxes, operational building expenses, and any underlying mortgage associated with the building itself.