Today I used illustrator, I have used Illustrator in the past and I have found that using the pen tool can very good but can take time to master. The major difference between Photoshop and Illustrator is that one focuses on the line art and can product some very high quality content, whereas Photoshop is more of an "All Round" tool for just about anything.
Image Trace and Untraced Gif
Image Trace is a tool in Illustrator where it takes the colors of an image and it converts it to shape for you. It like an automatic pen tool only it can sometime mess up and is not as accurate.