“Ethernet” is a protocol… or actually a set of protocols or standards that establish how network devices communicate. The name gets misused in the most technical sense, but most folks know what you’re talking about it they’re network geeks.
However… “ethernet cable” is just a cable. Comprised of twisted pairs, its use is not limited to networking. It’s just cable, be it cat5, 5e, 6, or whatever. My whole house is wired cat5e. I use it for both networking and phones depending on how I patch it into the patch panel. I’ve even used it for thermostat wire in a pinch, but that was temporary.