Butt, Tee, Corner, and Lap are types of joints. Fillet refers to the weld
or in your case the shape of the brazing alloy in the corner of your Tee or
The two most common welds are groove and fillet.
A brazed Butt joint would infer that the joining faces are bonded by the
capillary action in the joint.
You are mixing joints with types of welds or in your case brazing
I am sure AWS or similar code has resolved this more specifically.
Fillet is the term for the braze alloy structure formed in a fillet
joint or fillet weld. Is there a term for the braze alloy in a butt