u/Fancy-Ask-9264

I thought the Boolean difference was suppose to cut out part of the mesh, not join it.

I found a solution but it required me to use the solidify modifier, why is that?

I was watching a tutorial for some Hard Surface modeling and ran into a problem. He used. bool tools to remove part of his mesh like in the picture shown above. But his difference boolean removed it perfectly while mine added to the mesh? I only managed to fix it when I added a solidify modifier to the mesh, but his didn't require the solidify modifier so I'm just wondering why this might've happened. I made sure both objects had proper normals facing the right directions as well as both had the proper rotation and scale. Any Idea?