OK I know what a MTB cable is. But my question is on the difference between road bike brake cables. Specifically the ends.

In stock I have some road bike brake cables for my road bike. They sort of look like a large derailleur cable end. A cylinder with the end is squared off. But on the touring bike, same thing except the end is rounded.

What are the difference between the two (besides the ends )? Are they interchangeable?