The six major nutrients that the body requires are carbohydrates, proteins, lipids, vitamins, minerals, and water.

What is the major functional difference between the first three and the last three nutrients (listed above) in maintaining a healthy body?

The first three are major sources of energy, they can be broken down into glucose - the most used energy in the human body.

The second three do not provide energy but enable the other three's ability to be used as energy, which is the main functional difference between the first three (macronutrients) and the second three (micronutrients)