The difference in cardio-respiratory fitness and cardio-respiratory endurance is a very thin line. Cardio endurance the physical fitness of a person is measured.
It is termed as the ability of a person's body to send nutrients and oxygen continuously to all parts of the body when a physical activity (including lungs and heart) is done for a prolonged period of time. While cardio-respiratory fitness can be called as the fitness of the lungs and heart of a person's body.