Imagine a Stryper song.
You transcribe it onto paper, then go into a major studio.
The studio head tells you that you're going to make three versions of the song:
(1) A slick modern post-rock production, with muted drums and really slow, lots of layers.
(2) A totally necro Watain worship style with lo-fi production and bizarre tunings, and drums that sound like they're down the hall.
(3) A Dimmu Borgir style symphonic black metal version, played really fast with lots of keyboards and girly squee vocals.
So... it's still the same song. The composition is the same: Same chords, same notes, same riffs in the same order.
But the production has changed, depending on your taste. Some like necro-blak kvlt. Others love the Dimmu Burger sound. And 25 out of 100 people will "like" it (on Faceplant) if it's the modern rock sound.
Which is more important, production or composition?