Scratchboard

Scratchboard is an art technique where you have a surface with white or a color underneath a layer of black paint which you scratch away with a sharp tool to create an image. Sgraffito is a technique where you apply layers of plaster in contrasting colors to a surface and scratch it away. Both of these techniques involve scratching away the top layer, and specifically scratching the highlights, leaving the shadows as the solid black.

Photoshop vs. Illustrator

The main difference between Photoshop and Illustrator is that Illustrator is based on vectors, not pixels. This means that the resolution is higher than Photoshop, and if you make an object bigger it will not grow blurry like it does in Photoshop. Photoshop is specifically for editing photos, but you can create objects to go around it. Illustrator allows you to draw vector images of high quality. Illustrator also has some different filters than Photoshop.