Ethernet is for network connections and is not the same as USB. A hub for ethernet could be your router. Printers with ethernet ports connect to your router and are networked and can be shared with any pc on the network. They do not connect directly to your PC. Most of these have a USB port too and may have wireless capabilities. Ethernet v USB isn't really relevant.
I wondered why my HomeHub3 had so many ethernet connections.
My main machine is a desktop. I also have a laptop that is rarely used (it was a boon when my DT let me down). I've just got an ethernet cable for it, so I can connect direct to HH3, rather than wirelessly, hoping to make it quicker when on the 'net.
I might look into a home network at some point, just to link these items together,,,,, when I feel clever enough to understand it !?