[hnbear]

Tonneau is the flat cover for the bed. A cap is the n-shaped cover that encloses it, giving it a roof. Typically matching the cab body work, so overall looks more like an SUV.

Eg: http://trinity-motorsports.com/wp-content/uploads/2016/07/20...

[flopsamjetsam]

Thanks. I think here we call those "canopies."