A co-op (cooperative) is a building owned by a corporation, and buyers purchase shares in the corporation, not real property.

 A condo (condominium) is real property. Buyers purchase the unit and a share of common areas.

 In co-ops, you own shares; in condos, you own the unit outright.

 Co-ops—around 75% of Manhattan’s housing inventory.

 Co-ops became popular in the 20th century before condos existed; condos emerged more recently.

Sometimes, but only with board approval. Subletting rules vary.