Older AA had Copper battery cups with copper primers. If it was a silver battery cup. it was a reload primer regardless if the primer was brass colored or silver colored. I just loaded a number of old AA CF cases yesterday and the copper battery cup was in them.
Winchester has changed the appearance of their factory primers over the years. I have seen all copper, and silver cup with copper center. It is the copper center that keys me that it is a factory once fired, but that may not be absolute. I suspect Winchester sold all copper primers as components long ago.
As mentioned above, it isn't a cut and dry answer. They have changed the factory installed primers over the years. If you know exactly what hull you have as regards to the production time frame, it is easier to deduce what primer should be in the hull.
Below are variations of factory installed Winchester primers. The first pic is the current production and factory installed primers in AA's. Then the others are factory AA primers from years past.
These are current production Winchester 209 primers available to the consumer for reloading.
You can see the difference when you look closely. The factory primers always had a copper color somewhere. I do believe years ago, you could actually buy the same primer the factory used. This would be at least back in the early to mid 70's and maybe before.
Hope this helps and didn't make it more complicated.