My interpretation of endurance in general is the ability to "go longer" or "last longer." For instance, Power Hour is a muscular endurance workout - not necessarily meant to build muscle (although you could if you are new to strength training) but rather to condition your muscles to endure. While pure strength training would allow you to pick up something heavier (i.e. more physical strength), endurance workouts would help you be able to hold it longer without getting tired. Cathe once used the example of carrying a gallon of milk in the supermarket while waiting in a long checkout line. Makin' any sense here? As far as cardiovascular endurance, I think it's similar (someone better at explaining these things may want to jump in) in that you will be able to keep the intensity up for longer periods of time.