Many times the terms grommet and washer are used synonymously, but that is not the case. Both grommet and washer are used for different purposes, have different ways of installation and are made up of different materials.
Grommets are the flexible rubber loops that are used to allow wires to pass through them. Washers are small and plain circles with holes in them and are used to reduce excess friction in hardware.
Grommets are usually a two-piece set that requires compression to make it fit. Washers are just a single piece that is fixed with a machine specially created for washers. Grommets have more width and depth to them while washers are generally just a flat circle with a hole in the middle.
The usage of grommets is also way wider than that of a washer. A rubber grommet can be used for wiring and cable protection. Many people also use it to reduce the frequency of vibrating objects, for example fans and computers. Washers on the contrary are mostly used in between a nut and a bolt to create optimum friction.
While washers are usually made out of plastic or metal, grommets are created from rubber to prevent electrical risks. Grommets are also available in different shapes but washers will always stay standardized to their circular shape. Sizes of grommet and washer also differ. A grommet will mostly be bigger than a washer and easily distinguishable.
Grommet and washer are both distinct and one cannot replace the other in terms of functionality. As washers are created out of metals, they cannot be used to protect wiring and cables. Washers are important in hardware and construction whereas grommets are more useful in electrical equipment, manufacturing or residential purposes.
Even though rookies use the terms grommet and washer interchangeably, everyone needs to note the differences and choose the option that fits their purpose well.