Better to copy disk to disk or through image file?

Is it better to copy disk to disk (on the fly) or first make an image file then burn to disk? Does it matter?

Thanks for any thoughts!
i've found low-speed disk-to-disk (two reasons - to allow for lower write speed / less write errors, and to allow the error correction to read the best it can) is what i prefer, however doing an error correction enabled read to an image and then a low-speed burn from there would be the same (but takes longer).
Exactly what I found and have been doing. Thanks for the response!