The terms "pipe" and "tube" are often used interchangeably. However, there are important key differences. Tubes are measured by outside diameter, rather than inside diameter. Tubes will be hollow, like pipes, but their inner specification is not as important as the outer measurement. Tubes are often used in precisely measured areas that require a very specific outer size to be maintained, such as medical equipment. Pipes, on the other hand, are measured based on the inside diameter only. The nominal diameter (the inside diameter) is specified, as with tubes, but the outside of the pipe is measured in thickness rather than a...