What is the difference between the Preparer and Holder?

The Preparer is a job position that we add to all of our Glide templates. You do not need to use it in your Glide system, you can add more positions, remove positions and rename positions. Read all about job positions here. The preparer position is typically set up so you can record the person who is going to take responsibility for completing the job. Other positions may include partner, manager, reviewer etc. In all, you can set up 16 positions for each workflow system. You would do this a) to allow the user occupying the position to be linked to the job (great for dashboard filtering) and b) to allow you to automatically set the person occupying the position as the job holder.

The holder is a different concept which you can read about in detail here. Every job (or if your workflow system has multiple sub-systems, every sub-job) has a single job holder. It can only be occupied by one user at a time. It is designed to show the user that is responsible for the current stage of the job. Where Glide looks to report on how busy users are the system will look for jobs where they are the job holder as opposed to where they occupy a position. The job holder can be updated manually or automatically by the system when any workflow step runs, read about this here.