You should work in Valuer mode for recording comprehensive inspection data that is to be used for valuation or appraisal purposes.
You should work in Agency mode for recording inspection data that is to be used for valuation or appraisal purposes.
Each mode stores different fields and the data is structured very differently. Agent mode stores Listing data as one entity: The Listing. Valuer mode on the other hand stores data in multiple entities organised within Projects as explained here.