There is no canvas size in illustrator, only the artboard and work area. The canvas can be any size and I think the maximum work area is 5m.
Unlike photoshop, if you import an image it will retain it’s actual dimensions regardless of the resolution. For example: I scan the same logo at 100dpi and 600dpi and create two image files. If I place both of these in illustrator they will measure the same size on the artboard.
In photoshop the image will change size depending on the resolution of the document.
Hope this helps in some way.