Hornady and Federal each use some kind of secret voodoo powder to obtain their results without exceeding pressure limits. I can say that Hornady's 30-06 Light Magnum is not B.S. It is definitely a stouter load than what I can handload.

About powders, unless you see what can the powder comes out of you cannot tell what type it is or the composition. All you can see is physical shape difference (flake, ball, extruded,etc.). Just because two powders look alike does not mean they perform the same. Disassembling a loaded round and inspecting powder will tell you nothing unless you know exactly what type it is. Look through some reload manuals and see how many different powders there are and the differences in charge weights among them.

As far as lot numbers, same lot numbers are assembled with the same batch of components. If you find an unusually accurate factory load, you can stock up on this lot number and keep things the same. Lot numbers are more importantly for the manufacturer to isolate problems with production for recall purposes.