Ah yes, I could say figuring out what the towers do is part of the puzzle, but really the game should give you more details! Basically the disruptor tower doesn't directly steal any energy but it changes the colour of the beam, and other towers can get more energy from the red beam than the blue beam. Then you have the force field and magnet towers which steal energy in an area of effect, and the green buff tower increases the effectiveness of towers placed next to it, but doesn't directly affect the beam.
Thanks for the feedback!