Commercial real estate includes shopping centers and strip malls, medical and educational buildings, hotels and offices. Apartment buildings are often considered commercial, even though they are used for residences. That's because they are owned to produce income.
Industrial real estate includes manufacturing buildings and property, as well as warehouses. The buildings can be used for research, production, storage, and distribution of goods. Some buildings that distribute goods are considered commercial real estate. The classification is important because the zoning, construction, and sales are handled differently.
Land includes vacant land, working farms, and ranches. The subcategories within vacant land include undeveloped, early development or reuse, subdivision and site assembly. Here's more at Land Broker Transactions.