Adobe has worked with creative industry experts and the test design specialists at Certiport to identify the skills and concepts that are critical to using Photoshop effectively in a professional context. He also does photo realistic paintings completely with Photoshop. Validate your knowledge of Adobe Photoshop, the world’s most powerful imaging and design software. Patrick Lamontagne is a cartoon artist who does all of his work in Photoshop, including the line drawing part.
He primarily works in Illustrator and has written several books and recorded several courses about his workflow. His work has a completely different look and style. Von Glitschka is the best Illustrator artist I know. The link includes some of the process steps. The final look is much different then something created in Illustrator. I start the old fashion way with pencil on paper, then color it in Photoshop. I combine drawing and photography for my composite art. IF you decide that Photoshop is perfect for your drawing needs, then you MUST get a pressure sensitive table. What kind of drawing are you trying to create? What's the final intent for the drawing? Do you want a super sharp clean edge drawing, or something more organic? You have to answer those questions before you can get the correct answer.
When you draw in Illustrator you don't have to worry about any of that in the beginning. If you want to eventually print your drawing at 16" x 20", then you need to start with a document that big, at a resolution of at least 150 ppi (depending on how it will be printed). If you draw in Photoshop it is important to plan ahead for final output size. Photoshop drawings can be more similar to drawing with traditional media like pencils, or chalk, or paint, if that's what you want. The lines are very clean and sharp, which is great for logo design and illustration. Illustrator drawings can be scaled and printed at any size without loss of image quality. That means Photoshop works with pixels and Illustrator does not. Illustrator is a vector based application and Photoshop is an image editor.