usb0 is Ethernet?

I have discovered by accident that usb0 can be considered one with eth0.
Okay. I usually do not use Ethernet. Even the module is blacklisted. Now
I am lost with Network Manager (the one in Trisquel 7). I can not find a
way to have settings for usb0 that do not conflict with eth0.

Linux is about networking too. So it might not be unusual to have eth1
and eth2. What do you do in this case? In the GUI.