Final answer:
Active transport requires energy, with primary active transport directly using ATP, and secondary active transport indirectly dependent on electrochemical gradients created by the ATP-fueled primary transport. Passive transport, in contrast, involves no energy expenditure.
Step-by-step explanation:
What distinguishes active (primary and secondary) from passive transport is primarily the energy requirement. Active transport, encompassing both primary and secondary types, requires energy, while passive transport does not. Primary active transport is directly dependent on ATP because it moves substances against their concentration gradient with the assistance of membrane proteins known as pumps. On the other hand, secondary active transport does not directly use ATP but is still considered active because it relies on electrochemical gradients created by primary active transport, which did utilize ATP. So, while secondary transport is indirectly dependent on ATP, it is not directly fueled by it.