-the quality is not going to be the same, especially VCD is very bad quality, SVCD is better but uses many discs and DivX is good but not plays at standalone DVD players.
-the time you need to encode your movie from DVD to (S)VCD or DivX is about 5-8 hours, while with a DVD burner you can back-up a disc into an hour.
-with the DVD burner you can keep DVD menus and other extras.
As you understand the biggest differences are the time you need to backup a movie and the quality. The difference is also in the price of the DVD-R drive and blank discs, but if you can afford it, I believe DVD is the better choices.
