Coaxial cable is the physical cable that connects the Ethernet network. There are cables that have been specifically designed to carry a digital signal throughout a network. They can be used to send most any type of signal from radio signals, emails, streaming video, etc.
These cables are used to send signals from one network device to another. For instance, most users have these in their homes to provide them with cable television and high speed internet for gaming online.
Coaxial cables are made up the same whether they are digital or standard. They are a set of wires twisted together with an outer shell (insulated sheathing) which is then covered in a metal shield, and then sealed with a final plastic covering.
The main reason for the sheathing and shield is to stop interference from penetrating the network. Interference can be caused by machinery such as generators or factory equipment.
Some of these cables are called digital, however they are technically not digital themselves. They are simply better equipped to carry a digital signal. They are no different than the standard coaxial cable. They are both built the same way. The word digital in digital cable is simply a marketing tool to sell more cable. Even though it can carry a digital signal, it is still a coaxial cable.