The answer to 'difference between supply line' is that supply lines are the flexible pipes that connect a plumbing fixture, like a faucet or toilet, to the main water supply line in your home. The main differences between supply lines are the materials they are made from and the size of the pipe.
The most common supply line materials are braided stainless steel, copper, and plastic. Stainless steel supply lines are durable and long-lasting, but more expensive. Copper supply lines are also durable but can be more difficult to install. Plastic supply lines are the most affordable option, but may not be as long-lasting as metal. The size of the supply line, typically 1/2 inch or 3/8 inch, will depend on the fixture it is connecting to the water supply.