In Illustrator, you can make a rough sketch of something using a regular mouse (via the Pen tool), and it turns the line/shape into points, which you can then move around freely until you have precisely the shape you want. You can then save that img out, and then just drag the points around more to animate it, then save out another img - and so on.
The advantage of this is that it's much cleaner, and fluid with more control over the shape you're working with. In photoshop it takes erasing, recoloring, and it's generally more challenging to move solid sections. (=