Let's be clear, it's not the same as conducting a concert band; or any other traditional type ensemble. This is the world of Jazz and perhaps its ethics speak for themselves. But if not, then let me spell it out: compared with the classical world with its engrained heirarchy, this is a world which permits the free expression of each individual player; or at least to a degree.The idea of having to defer to an authority figure is anathema to jazz players; although nothing is completely clear cut; because there is a requirement sometimes for someone to take responsibility for that dubious practice called directing. Note that I didn't say conducting. Surely a conductor is someone that dominates the proceedings, from the front, part of the pagentry perhaps but also an important requirement in the absence of a rhythm section whose throbbing beat lays down the pulse to which all defer.
So...directing is different from conducting. Well, I would say so: one is dominant...the other is making suggestions to the players; like 'do this or it will all end in disaster'. I'm joking. The difference is as stated above: that one has a rhythm section to keep things straight, whilst the other doesn't. A Jazz director should not have to keep time; unless of course there is a change of tempo or a slowing down or perhaps some kind of rubato free form. In such circumstance, someone is needed to keep the ensemble together, playing at the same time, however that is presented.
Jazz directors are also handy for reminding the ensemble of any dynamic considerations, cueing different sections or soloists in, dealing with pauses (fermatas), keeping an eye on the overall balance, rather like a sound engineer and generally ensuring that quality control is maintained. And they are most likely given the job of presenting the band, communicating to the audience, cracking a few jokes etc...
But this is not the world of classical conducting. To attempt such a thing in the Jazz world might inspire a mutiny though it depends on the extent to which it is administered. Remember Jazz is supposed to be about individual expression to a certain extent and there should always be scope for improvisation at least some of the time.
