Both can be erasers, but the specific usage and explanation are different. Eraser is American English. Translated as an eraser, especially an eraser on stationery. This is a countable noun. In addition, there is the definition of blackboard eraser. Rubber is mostly used in British English, meaning "eraser" for wiping pencil or ink marks. This is a countable noun. In addition, rubber also means "rubber" or "synthetic rubber", which is a material term and cannot be counted.

Rubber:

Eraser is stationery made of rubber, which can erase traces of graphite or ink. There are many kinds of erasers, with different shapes and colors, including ordinary erasers, special erasers for art, such as 2B, 4B and 6B for painting, and plastic erasers. 1770 British scientist Priestley first discovered that an eraser can erase pencil words. The raw materials of rubber are rubber or plastic, sulfur, vegetable oil and gravel.

Some pencils have a small eraser at the end. Most of these erasers are pink, but it is easy to damage the paper with this eraser. Another kind of eraser is the brown eraser commonly used by artists. It is made of soft and rough rubber, which can be erased in a large area, but this eraser can not erase handwriting effectively and accurately. Another artist often uses soft rubber. It is mainly made of a gray material, which will not leave residue after use, so its life is longer than other erasers.