Venue promoter vs. Booking agent

I am confused by this. Can anyone help?
I would like to issue an article on my blog on this subject
why some bands have booking agents and why some bands depend on venue promoters.
And what do venue promoters actually do? I know they find the bands and actively promote the shows
but do some venues only work with their promoters to fill up the slots?
How about booking agents, do they work with the bands in respect to promoting the show? do they promote anything? do they only seek the gigs?
Whats the best way to deal with these ppl?
thx alot
I would like to issue an article on my blog on this subject
why some bands have booking agents and why some bands depend on venue promoters.
And what do venue promoters actually do? I know they find the bands and actively promote the shows
but do some venues only work with their promoters to fill up the slots?
How about booking agents, do they work with the bands in respect to promoting the show? do they promote anything? do they only seek the gigs?
Whats the best way to deal with these ppl?
thx alot