I've had the opportunity to be both, and currently I am the M.D. of the church I play for. The Musical Director must work well with the Minister of Music first and foremost. The M.D. is responsible for getting the songs from the M.O.M. and then making sure that they learn every part. As the M.D. you should know what every other musician in the band is supposed to be playing, so that during rehearsal you can make corrections as necessary. This is not saying that you need to be able to actually play their instrument, but you should be able to explain exactly what you want to hear. Often times I have our band learn the music exactly like the CD, and then when we get together for band rehearsal I will make some changes to fit us as a group, or just to livin up a simple song. Hope this helps.
