Instead of using toner and paper like a laser printer, or ink and paper like an inkjet, film recorders write on photographic film with a beam of light. Lens Camera back Software for your computer, Computer circuitry, power supply, and other odds and ends to make it work. Most film recorders are digital, therefore like printing to your laser printer, the film recorder works from the computer data, not the computer's screen. This allows phenomenal resolution. Determining your Requirements when Selecting a Film Recorder.
Faster turnaround can cost a lot more per slide.
With your film recorder in house, you can image the slides in an hour or two. Now all you have to do is find a lab. I have known occasions when people take the film out of the machine, catch their flight, and find a photo lab in their destination city to develop the film. In house film recorders allow you last minute changes. You just cannot find a service bureau that will image, develop and mount a roll of film, all in 3 hours.