Hollow Cylinders are defined as follows:

There is a difference in the way hollow cylinders are measured or specified, and the way hollow cylinders are measured or specified is dependent on what they are intended to be used for. Everything comes down to the manufacturing processes and how you want natural process variation to be distributed throughout those processes. The consistency of the bore or the consistency of the outside diameter can be achieved, but not both at the same time. At the very least, not with a high degree of accuracy.

The majority of smaller bore metal pipe and seamless aluminium tube is manufactured through the process of extrusion. When a billet of material is squeezed through a die, it produces a long length of material with a uniform cross-sectional shape. Extrusion works best with ductile materials, which is one of the reasons why aluminum is produced in such large quantities.

Extruding pipe or seamless aluminium tubing involves forcing metal around a mandrel, which results in the creation of an internal passageway in the finished product. Because it is difficult to maintain the internal bore's concentricity with the outside diameter in practice, the wall thickness of the internal bore varies. In most cases, the manufacturer can control only one of these two parameters: the bore or outside diameter.

Several tubes will be drawn after extrusion (or, in some cases, in place of extrusion) in order to thin them down and improve dimensional consistency. Unlike extruded material, drawn material is pulled through a die and over a mandrel in a manner similar to that of extruded material, the difference being that the material is pulled rather than pushed through the die.

Extruded round pipe can be used for a variety of applications.

One of the most common applications is in heat exchangers, which is a common occurrence. Due to the fact that aluminum has excellent thermal conductivity and is simple to weld, it is used in this manner. For this reason, it is in high demand for solar water heating systems that do not impose an undue burden on a roof.

Extruded aluminium seamless pipe has a wide range of applications.

Extruded aluminum seamless aluminium tube is used in a variety of architectural and structural applications and can be found in a variety of configurations. Handrails, support columns, gate and fence posts, and other structural elements are all examples of what is known as structural elements. Furthermore, it can be found in trailers and other transportation applications where weight is a concern, and it can even be found in electrical bus conductors.

Aluminum Tubes and Pipes are available in a variety of sizes and shapes.

The vast majority of aluminum seamless aluminium tubing and pipe is extruded from aluminum alloys 6061 and 6063 in grade. The reason for this is that they have a low tendency to work-harden, allowing the extrusion equipment to run more quickly. Because of its finer grain structure, 6063 generally has a better appearance than 6061, despite the fact that 6061 is stronger. It also anodizes well when a colored finish is required.

It's the same, but not the same as

However, as previously stated, pipe and aluminium seamless pipe are not the same thing when it comes to hollow cylinders. The fundamental difference between pipe and  is that pipe makes use of the inside and tube makes use of the outside.