The difference would involve creating a variable to store the image, loading the image, (potentially) resizing the image, and displaying the image. It's not that difficult, and you can display the same image three times.

It's pretty easy to do that.  First you need to use loadImage() somewhere in setup() to load the image of the balloon and assign that loaded image to a global PImage variable.  Then instead of drawing with rect(*, *, *, *) you'd do image(balloonImage, x, y).