The American Welding Society has set up guides to define these
terms. Soldering is joining metals by melting the filler metal only.
Brazing is a method where the heat opens the “pores” of the base
metal to allow infusion of the filler metal.Welding is when you melt
both the base metal and the filler metal to join the materials. They
Also have defined the temperatures which control these processes. I
do not remember what they are. I retired form the Welding supply
business many years ago. I do have my senior moments too.
What most jewelers do is BRAZING.
A brother-in-law of mine was in the industrial lead acid battery
business( they were building & Repairing very large batteries),
several years ago. He regularly “Welded” lead, using a torch to melt
the adjacent metals together. Thus temperature is not necessarily a
truly definitive test. Mark Chapman