What is the difference in passive transport and active transport?

Answer 1

Active Transport is when the cell uses energy to pump a solute across the membrane against a concentration gradient (the place where the density of a substance decreases). Passive Transport, on the other hand, does not require the cell to use energy to move things in and out of the membrane because of diffusion (where molecules move until everything is spread out evenly).

Think of it like barrels on a hill. You're actively using energy to push the barrel up the hill (when the cell pumps the solute against the concentration gradient) but no energy is used when you passively let it roll down (the solute rolls away from where everything is concentrated by diffusion until both sides of the membrane are equal to each other).
Active transport requires energy.

Answer 2

Energy requirements.

(Should be zero for passive).