FYI the majority of batteries sold in the US are made by one company: Johnson Controls. This includes most batteries sold at auto supply stores, Interstate, Die Hard, Walmart , Costco, Bosch and they recently bought Optima and Varta.
The other 2 mfg in the US are Exide and Delphi.
Google "who makes batteries in the US" for more info.

 

Good to know and makes sense because of environmental compliance, etc. That being said, there would be variance in each specification but as we've seen some batteries are simply rebranded versions of the same thing.