They are all international metric units, except that liter is a unit of capacity and liter is a unit of room volume. They have different names, but the essence is the same.

One liter and one liter are equal to 1000 ml and can be converted to each other.

This knowledge is often used in mathematics. Although l and l have different names, they mean the same thing. One liter is equal to one liter. Don't convert them wrong.