People seem to be making a point of the distinction of the role of Engineer and Producer. What's the difference?
The engineer is the "equipment operator". His expertise is choosing the right equipment for the job and using it in the right way to achieve the desired effect. His role is analogous to that of the cameraman in film production.
The producer is kind of like a project manager. His job is to get all the individuals - musicians, vocalists, engineers - to each do their part to achieve the overall goal.
For example, he might decide a certain song should be quiet and soothing, so he'll advise the musicians to tone down the accompaniment, the vocalist to soften her voice, and the engineer to add the necessary processing to achieve that soothing sound he's after.
2I believe THE Bruce Dickinson would put it this way: More cowbell!– user13Dec 8, 2010 at 16:43
Producer, engineer, mixer Phil Ek has described audio engineering as the "physical recording of any project—the placing of microphones, the turning of pre-amp knobs, the setting of levels—and the producer is the guy who directs that process."
Producer says: "Make the bass beat phatter". The engineer does it.