Old metallurgical engineers and steel manufacturers say:

Manufacture countless daily items with steel plates. Thickness varies widely; extremely thin slices are considered foils or leaves, and slices thicker than 6 mm (0.25 inches) are considered steel plates.

Sheet metal parts can be divided into flat parts or ribbons. This can be hot rolled strip (1.2mm-16mm) or cold rolled strip (0.2mm-4.2mm).

In most parts of the world, sheet metal thickness is always specified in millimeters. In the United States, the thickness of sheet metal is usually specified by a traditional non-linear gauge (called a gauge). The larger the specification number, the thinner the metal. Commonly used sheet metal sheet metal ranges from 30 (0.30mm) to 7 (4.55mm).

It is a general term (widely used) in construction, design, maintenance and overhaul, not a defined term.

A piece of cotton is a very soft cut cotton, the size is suitable for any standard size bed, right? Yes, so is the steel plate. Standard width (metric and ANSI), sold by length or steel coil. The thickness is numbered according to the gauge. Very soft steel plates must be manufactured or bent into a certain shape or welded together. Can not stand on the edge, must be used flat. Usually sold according to surface treatment specifications or polishing definition

Now, its thicker uncle is a steel plate. Again, although thickness is usually a defined term, it is still sold by name. Always specify by alloy name and (or internal) certification and heat number tracking. The printing plate is thick enough to stand safely on its edges and can be stored upright, but is almost always pressed into the final product after compression molding, machining or cutting, welding or molding. The length and width must be noted.