Hi Joe
These three are identical and all have are the same obverse design IMO. The pins do differ as you note. The one on the upper left has different, deeper knurling when compared to the other two. Another difference is the attachment method. The upper left one has a "U" shaped curve and slightly flattened at the end and soldered to the reverse. The others have a type of upside down "L" shape and directly soldered using the end of the pin.
