If what you want to do is create pictures, the two basic kinds of design software are raster and vector. With raster, you are creating a picture pixel by pixel, and can do all kinds of special effects. This is what Photoshop and similar programs can help you to make.
With vector programs you are making shapes based around lines rather than squares. And these lines can be resized and manipulated as much as you like. Clipart is usually made with vector graphics, which is why it looks like cartoons. It's basically line art with color in the closed shapes.
Both have their advantages and disadvantages and you just have to decide which is best for individual projects. I often end up using vectors as a base and then finishing off a design using raster graphics design software.