[DonRotolo]

Welding is when you fuse parts together by melting them.
Brazing uses a different material to join parts. It is also known as "Hard Soldering", while the lead-tin based solder (like that used for electronics) is called "Soft solder". Brazing rods for steel are often made of brass.

Brazing is a lot stronger than soft solder, but far weaker than welding. Aluminum brazing is very challenging to do well, while steel is very easy for a beginner to master. Steel can be brazed with a MAPP or Acetlyene torch, but propane is not hot enough. In school we had a natural gas torch that added compressed air to make the flame very hot, and used that for brazing.

There are adhesives that exceed the strength of brazing in aluminum.