What is the difference between digital impressions and CAD/CAM?

There are four systems currently on the market (3M ESPE Lava Chairside Oral Scanner C.O.S., CEREC AC, E4D Dentist, and iTero) that allow the dentist to take a digital impression in place of a traditional elastomeric impression. CAD/CAM (computer-aided design/computer-aided manufacturing) refers to the fabrication of the restoration. CEREC AC and E4D Dentist offer the option of in-office design and milling. Many dental laboratories are also integrating CAD/CAM technology to produce restorations from a variety of materials.