The direct proportional function is Y/X= constant, the general form is Y=aX, the inverse proportional function is xy= constant, and y=a/x, which is a formal difference. Another difference is that the positive proportional function increases when x increases and decreases when y decreases, and the inverse proportional function increases when x decreases and decreases when y decreases. Of course, the images are different. The direct proportional function is a straight line and the inverse proportional function is a curve.