What is the difference between electrofusion connection, hot melt connection and welding connection?

Hot melting is to heat and melt the materials with special equipment. After the materials are cooled, they are connected into one body. Generally, hot melt pipe fittings are made of hot melt in the project, which is convenient and economical to construct. Electric melting is actually a type of hot melting, and the heating coil is preset in the material. Electricity is applied to heat and melt when connecting. The welding quality is good but the material is more expensive. It is suitable for occasions where it is inconvenient to use hot melting equipment or the welding requirements are high. Welding is to fuse other solder and the parts to be connected. The most common is the welding of metals. , weldable plastic sheets, etc.