[STILL UNSOLVED] Tracking changes between tables

Here would be the query for Overview

let
    Overview = (f)=> let S = Excel.Workbook(f),
    Overview_Sheet = S{[Item="Overview",Kind="Sheet"]}[Data],
    #"Promoted Headers" = Table.PromoteHeaders(Overview_Sheet, [PromoteAllScalars=true])
in
    #"Promoted Headers",
        Source = Folder.Files("C:\Users\xxx\Downloads\Test folder"),
    #"Added Custom" = Table.AddColumn(Source, "Custom", each Overview([Content])),
    #"Removed Other Columns" = Table.SelectColumns(#"Added Custom",{"Name", "Custom"}),
    #"Expanded Custom" = Table.ExpandTableColumn(#"Removed Other Columns", "Custom", {"Report Entry Date", "Project Name", "Project ID", "Programme ID", "Project Stage", "Start Date", "EIS Forecast", "AFC Baseline (£m)", "Current AFC (£m)", "Project Maturity ID", "Configuration State ID"}, {"Report Entry Date", "Project Name", "Project ID", "Programme ID", "Project Stage", "Start Date", "EIS Forecast", "AFC Baseline (£m)", "Current AFC (£m)", "Project Maturity ID", "Configuration State ID"})
in
    #"Expanded Custom"

This will load the snapshots into a single query.  Next you need to decide which columns to compare from the Overview sheet. For example the project stage: