I'm posting some photos of the YUASA YTX20L-BS and Walmart ES20LBS for you to compare. The cases appear to be the same.
The tops look the same except the Walmart EverStart has a label. the label contains charging instructions and model number YTX20L-BS, which happens to be the model number of the stock YUASA battery.
The tops are shaped the same the +/- markings are pressed in the same. The posts are the same, both accepting the threaded inserts from the ends. The filler covers look the sane.
I removed the filler cover and looked at the mechanisms that are used to puncher the Dry Charge Acid Seals and they are the same.
From the top, the Walmart ES20LBS appers to be identical to the stock YUASA YTX20L-BS.
The case shape and dimensions are identical. The front labels are different. But the rear labels are identical except for one stamp on the EverStart label. The labels even share a stamp (5PSYMBWPO) on the lower right corners.
The cases also have engraved characters on the top rear that are very similar.
If the Walmart ES20LBS is not manufactured on the same line as the YUASA, I'm gonna be surprised.