The difference between pipes and tubes is simply in the way it is sized.
These sizing schemes allow for universal adaptation of transitional fittings.
1/2" PVC on the other hand is not the same size as 1/2" tubing, and therefore requires either a threaded male or female adapter to connect them.When used in agricultural irrigation, the singular form "pipe" is often used as a plural. Pipe is available in rigid "joints", which come in various lengths depending on the material.
The schedule is largely determined by the operating pressure of the system, with higher pressures commanding greater thickness.Copper tubing is available in four wall thicknesses: type DWV (thinnest wall; only allowed as drain pipe per UPC), type 'M' (thin; typically only allowed as drain pipe by IPC code), type 'L' (thicker, standard duty for water lines and water service), and type 'K' (thickest, typically used underground between the main and the meter).
Because piping and tubing are commodities, having a greater wall thickness implies higher initial cost.
In other words, 1 foot of 1/2" L copper has slightly less volume than 1 foot of 1/2 M copper.Źródło: https://en.wikipedia.org/wiki/Plumbing
A pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-section, used mainly to convey substances which can flow ? liquids and gases (fluids), slurries, powders and masses of small solids.It can also be used for structural applications; hollow pipe is far stiffer per unit weight than solid members. In common usage the words pipe and tube are usually interchangeable, but in industry and engineering, the terms are uniquely defined.Depending on the applicable standard to which it is manufactured, pipe is generally specified by a nominal diameter with a constant outside diameter (OD) and a schedule that defines the thickness.Tube is most often specified by the OD and wall thickness, but may be specified by any two of OD, inside diameter (ID), and wall thickness.Pipe is generally manufactured to one of several international and national industrial standards.1 While similar standards exist for specific industry application tubing, tube is often made to custom sizes and a broader range of diameters and tolerances.Many industrial and government standards exist for the production of pipe and tubing.The term "tube" is also commonly applied to non-cylindrical sections, i.e., square or rectangular tubing.In general, "pipe" is the more common term in most of the world, whereas "tube" is more widely used in the United States. Źródło: https://en.wikipedia.org/wiki/Pipe_(fluid_conveyance).