The main difference (as I understand it) is that Photoshop works in pixels whereas Illustrator works with vectors. What this means is that in Photoshop the more you enlarge a drawing, the more fuzzy and indistict the image is. In Illustrator that doesn't happen because they are vectored paths. I could blow the drawing up to the size of the actual aircraft (If I had a big enough monitor) and it would still be just as crisp.
I'm working in this manner because I'm new to BOTH programs, and it's the only way I understand how to work with lines at the moment. To move the entire image over to Photoshop, go up to File>Export>Photoshop in CS and beyond. Photoshop is automatically opened and you will get all the lines on a transparent background exactly as origionaly drawn.
