Lee Loader

I purchased some once fired Winchester AA HS hulls from Precision and was checking them out. I found some marked "light" and some (mebbe 25%) marked "heavy". I'm assuming these markings, printed on the side of the hull are just designations of the original factory load, like +P headstamps? I sectioned and inspected/measured a couple and I found/could see no difference in brass, hull, or base wad. I'm not one to assume much of anything connected to reloading, so, am I right/wrong?

I don't know 100% but .....
Winchester AA are in 3 flavors , it's unlikely you'll ever the paper base version .
There is a 1 piece and 2 piece the 2 piece are used for Handicap and 2? gram (3/4 oz) competition loads .
The one piece is used for everything else . The light and heavy is most likely for 7/8 oz vs 1 1/8 oz .

Driloks have a different base and slightly different data , being designed specifically for steel shot .
The super speed cases share data with both depending on components .

I can't say this enough although the industry standards are making the 209 primers closer substitution is very much discouraged from data . The Winchester 209 replaced with a Federal 209A (20yr ago) in certain combinations could raise pressures as much as 10,000 psi . Kind of a big deal when a load jumps from 8,900 psi to 18,500 in a 15,000 psi maximum cartridge . The FC 209A used to be the highest pressure/hottest spark primer and WW 209 the lowest pressure/longest duration primer .
The WW mag was only a tiny bit hotter than the FC 209A and FC has a Mag version . Of course there is a place to make the substitution but its only useful really for diehard cast iron waterfowlers that start with teal and woodies in September and end with snow geese in February on the north side of the Mason-Dixon . Generally hanging out in blizzards ...........

RBHarter would be correct the Light and Heavy refers to the shot charge weight. Back in the day when I used to reload shotshells I used the same Win. AA hull for 7/8 to 1 1/4 oz. loads.