FusionPro's new naming scheme has made their offerings a little confusing. Basically it's Creator > Producer > API. Creator is the desktop Acrobat plugin. Producer, from my understanding, is basically just the composition engine running on another workstation on-site. API is their web2print offering which is hosted off-site. Producer is useful if you run really long complex jobs and want to off-load that to a different machine. It also gives you the option to pause and prioritize running jobs. If you have jobs that typically take more than an hour to finish composing Producer is something you might want to look at. Although with 4 licenses I'm sure you can move these long running tasks to one of the workstations that is idle. From some of the sample files I sent PTI, Producer was able to process them 3-4x quicker than my workstation. And the pricing reflects that.