DC discs are based on CD technology. What Sega did was basically make the spacing of the spiral on the disc smaller to squeeze in more data. Sort of like what was done with 80 min CD's and even the insane 99 min ones. The laser used in the DC is just a standard CD laser every CD-ROM drive out there has. When you use the DC GD-ROM burner you are providing it with a standard Mode 1 (or 2 can't remember) ISO image. Of course a DC disc also has two sessions because of it's nature.
GC uses a standard DVD laser. The discs are for all intents and purposes regular DVD discs. With the exceptions I mentioned earlier. Heck you can even have dual layered GC discs if you wanted to. The size thing isn't really an issue. If you ever found a way to get the GC to read the disc there are mini-DVD-R's out there that will fit a GC game nicely. And if not you could just use a regular DVD-R disc with the GC's case taken off.
GC uses a standard DVD laser. The discs are for all intents and purposes regular DVD discs. With the exceptions I mentioned earlier. Heck you can even have dual layered GC discs if you wanted to. The size thing isn't really an issue. If you ever found a way to get the GC to read the disc there are mini-DVD-R's out there that will fit a GC game nicely. And if not you could just use a regular DVD-R disc with the GC's case taken off.