The USB protocol makes a strict distinction between devices and hosts, and allows connections only between each other, but not between the same type.
A USB MIDI device works only with a PC/laptop. The USB cable connectors are designed to work only one way to enforce this restriction.
There are special "USB MIDI Host" devices (made, e.g., by Kenton, Midiplus, and Miditech) that contain a USB host controller, but those aren't cheap.