I’m not so sure about food, but for many mass market products it is indeed true that the same manufacturer can be engaged to make the same product under different branding. The difference then comes down to the corners cut to meet the client’s pricing. Crappier boxes, thinner bags, packing material, and quality inspection. Assuming the core ingredients are not compromised in some way.
What I’m seeing is that China’s subsidies create cheaper products that benefit consumers, be it Chinese or the world at large.
Meanwhile American subsidies to American companies benefit their CEOs who then cut themselves an obscenely fat bonus, and fire half their downline staff.