Copper Tubes

Copper tubes size is measured by the outside diameter (which includes inner diameter and wall thickness). On the other hand, copper pipes size is measured by inside diameter. Copper tubing comes in varying shapes like rectangular, square, and cylindrical, but copper piping comes only in round shapes. 

While soft copper tubes are ductile and easy to bend which enables easy flow of product, the rigid copper tubes are usually referred to as ‘pipe’ because they are hard, non-ductile, and require elbow connection. Soft copper is the only type used as refrigerant line HVACs whereas rigid copper is mainly used for water lines.