The Field Info tab contains information about the control the field is based on. This tab contains information useful to the Scripting Support team should you log a support request:
Field Name
The programmatic name of the Field. It isn't ever displayed to the agent, and is only used for programmatic purposes such as referring to it in other Fields, manipulating it with code, or recording its data in the database at the end of a Workflow run.
Note that if this Field Name is referenced by any other controls (such as in JavaScript in a Calculate, or as a parameter for a Date's Minimum Date), then should the Field Name be altered it will also need to be updated in the referencing Field and re-saved.
A unique reference ID for the Field, this is the unique identity of the Field within the Scripting database. It can be useful when troubleshooting Workflow issues using Internet Explorer or Chrome's developer consoles (where alerts may refer to F123 etc, where the numeric portion of that is the Field ID).
This expandable panel is only visible if the selected Field has been replicated in the Workflow as a Used Control. If so, all instances of the Field will be listed here.
The Control Information panel contains system information about the Control that the Field is instantiating. This information can be helpful for certain support requests.