/diy/ - Do It Yourself

I'm working on a personal project that isn't a normal repair or assembly, and I need to go to the store and ask for help. What I need to know before I go to the store is what is the difference between a pipe and a duct and a hose. I have social anziety so I have to be prepared with a little speech that will work in the store. If I ask wrong and he just stares at me I really start to fall apart.

Pic relates is not the part I need btw.