My two cents worth:
From the bottom photo the top revolver looks to be a BFR factory grip and the bottom revolver looks like the grips are slimmed on the bottom on the small end (no grip frame mod?) but also quite a bit on the big end (grip frame mod-yes.)
Is the bottom one a JRH Mod?
No, they are all BFRs -- factory BFRs. The bottom photo shows the "plowhandle" above the new "Bisley." Sorry, should have clarified.
Huntington makes a true custom grip for your hand and also subtly re-contours the grip to give you a little more space between the grip and the back of the trigger guard. It's really subtle but extremely effective.