Well not quite - marsala would be for drinking (better quality), while marsala cooking wine would taste pretty much the same but be a poor quality. Much like your 75$ red wine and cheapo cooking red wine - basically its the same product (red wine) but the difference in quality dictates the useage.
But I never saw Marsala cooking wine here in Sing only the popular Marsala. If you want to make a desert, you will need the more expensive one without salt...