Differences between fat free mass and lean body mass?

Please don't search your answers here for Primavera. Use your reading materials provided. A certain amount of body fat is necessary, as it regulates body temperature, cushions internal organs, helps with shock absorption during exercise and stores caloric energy. According to the American Council on Exercise, between 10 to 13 percent body fat is essential for women. Other classifications include athletic, or 14 to 20 percent; fitness, 21 to 24 percent; and average, 25 to 31 percent. Essential fat is the bare minimum needed for bodily function.

Lean body weight refers to the sum of the weight of your bones, muscles and organs