If you want to understand what a T1 line is, let me give you an example of normal phone line which most of us familiar with it. A normal phone line transmits your voice through copper lines as analog signal. But if you want transmit or receive data instead of voice you need to use a modem. The speed of transmission in this situation is only about 30 kbps.
Now a days, almost all telephone companies use digital signals instead of analog. These signals are delivered through fiber optic lines, although copper wires might be used. The speed of digital signal flow is 64 kbps.
Now a T1 line can transmit voice through digital signals via 24 digital voice channels and the speed of data in T1 line facilities is 1.544 mbps. A business T1 line is very reliable comparing to normal modems with 60 times higher speed. In order to use a T1 line you require digital connection device called Customer Switching Unit (CSU) or Digital Switching Unit (DSU).
A full business T1 line can handle up to 200 users to use one T1 line. Therefore business T1 line is for small agencies and companies. T1 line is not suitable for individual and home use because it is expensive for them; the best option for them is to use DSL services.
An Ethernet connection is generally defined as direct connection of network ready devices to a network. A network ready device means a Network Interface Card (NIC) is installed in that device.
For companies that need more bandwidth and speed a business Ethernet is the best option. Although it is more expensive than business T1 lines, but it provides more flexibility and a solution for their large bandwidth requirement. Business Ethernet service is available at different speeds of 3 mbps, 5 mbps and 10 mbps.