In the Advanced Designer, why the number of Predicted and Reference Fields, and the Fields in the JSON output, is different than the number of created Fields?
The Fields show all the Fields created for this skill. Let's say there is a table with 5 columns - this table will count as 5 Fields. But in the reference document, 2 lines in this table are marked - it will count as 10 Reference Fields.
The Predicted Fields column shows the predicted number of found Fields if the document is processed by the created Skill.
The created Fields are also not related to the Fields being extracted for each document. When the Extraction Rules Activity is created, it is possible to specify what Fields among the created Fields should be extracted by this Activity. So each Activity may extract fewer fields than created for this Skill. This may result in the export file having fewer extracted Fields than created Fields.