difference between soldering and welding

Soldering and welding are both ways of joining two metal pieces together, but they work differently. Soldering works by melting a metal called solder (a soft, malleable metal alloy) in between two metal pieces. The metal pieces stay joined as the solder cools and hardens. Welding melts both pieces of metal using very hot flame or electricity until they form a single piece. The metal pieces are fused together, like two drops of melted metal that have become one.