Pipes and tubes define objects that are fairly similar, however, they can be used in different situations. Pipes are usually rigid hollow cylindrical constructions made of metal, concrete, plastic, or other materials. They are used to transport large amounts of liquids/gases over a great distance. Pipes (especially public service ones) often run underground, therefore, they are manufactured from materials that are very resistant to any type of damage. However, pipes are not limited to public services and may be used in other applications as well.
The word "tubes" can sometimes be used as a synonym for "pipes", but there is a minor, yet important disparity. Pipes have different engineering requirements, they are produced from lighter and more flexible materials. There are bendable and non-bendable tubes, and they are often used as supplementary elements in various devices and systems.