However, the application rates appear to be the same, so, perhaps the two companies are measuring the "active ingredient" differently??
Bt. Right now I am using "Hi-Yield" I have used Southern Ag before. If you look at the label sometimes they use toxins generated by the bacteria, sometimes they include the spores and bacteria or they might have them in different proportions. I suspect that by now my Bt. does not have any live Bt, it being several years old. I assume the toxins are still toxic to caterpillars. The Tomato plants I sprayed stopped being eaten so it was either the Bt or a bird.
I remember the first time my Father used BT on cabbage. It was powder or dust that you sprinkled on the plant and hoped that the loopers ingested it. Sprayed BT has much better coverage.
I suppose that in the end you make your choice based on how much you want to pay and how often you will be using it. I hope it works!