What is the difference between non-woven fabrics and felt?

What is the difference between non-woven fabrics and felt? Felt can also be called non-woven fabric, because the equipment and process principles used in their production are similar, but the production process and equipment of felt are quite simple, basically produced with waste raw materials. Felt generally refers to thicker products, more than 500g/m2. The cloth felt is usually formed by acupuncture. Even if the surface is pressed, there are pinholes, and it is cut in the middle. It is more obvious that the cloth surface and the section are vertically stretched by chemical fiber. The needle felt is too thick and layered, because it is a combination of several layers of acupuncture, not formed by acupuncture, felt does not have the above characteristics.