What is the Difference between Stub-inn and Stub-on.

Stub-in is when the branch pipe goes inside a hole cut into the main pipe and is welded with a stronger weld, making it suitable for higher pressure and permanent connections. Stub-on is when the branch pipe sits on the outside of the main pipe and is welded with a simpler weld, making it easier to install but generally weaker and used for lower pressure or less critical applications.