Although the words sound similar, the internet and an ethernet are two completely different things. An ethernet is the physical wiring which allows access to the internet. It is a Local Area Network access. The main difference between the two, the internet and ethernet, is the fact that internet is a wide area network which is also called a WAN.
The internet is a worldwide large area network that allows the connection to many devices all around the world. An ethernet allos the access of local. They are both networks which allow for connecting, however. Ethernet is a standard by which devices can actually connect to the internet.