When talking about CD media, it's the same thing. Burning is just another term for writing because it physically burns the recording layer to reshape its surface.
If you were thinking of imaging to a hard-disk, that's different entirely; that is the use of software to take a snapshot of an entire drive and save it as a more backup. It's quicker and more compact than cloning a drive's contents.
Hope my slight digression hasn't muddied the waters.