The first summer of covid, when there were all those supply chain shortages, I read an article on the shortages (I think in the NY Times). They explained that some of the shortages weren't that the companies were short of an item, just short of that item in a format conducive to home use or preference, and that sometimes they lacked the flexibility to move that stock to the consumer.

Like, there was a massive home toilet paper shortage, but companies were sitting on stocks of commercial toilet paper that they couldn't move: it wasn't properly packaged for individual resale, couldn't be easily switched to a different packaging, was often thinner or rougher than home-use paper, came in massive rolls that didn't fit on a home spindle, and most people couldn't, wouldn't, or didn't think of trying to get commercial toilet paper.

Anyway - one of the mis-matches they talked about was popcorn. People were in lockdown, wfh, etc, and the home popcorn kernel market was exploding - there wasn't enough stock. At the exact same time, however, movie theatres were closed and huge stocks of movie theatre popcorn kernels were going unsold. And they couldn't move the movie theatre popcorn into the home market.

Movie theatre popcorn uses a different variety of corn than home popcorn does. Like, one type of popcorn has a mushroom-shaped kernel that produces a large round shape with lots of surface area and is pretty crisp, while another one produces a butterfly shape with lots of edges sand that melts easier in your mouth. And if you've built your brand recognition around one type of popped corn, you can't just suddenly substitute in a different type - people will notice, and complain.

Aside from the main types of popcorn kernels, I'm pretty sure there are subtypes as well. Just like eating apples include premium types like cosmic crisp and 'common' types like red delicious, I'm sure that there are premium and 'common' varieties of home popcorn kernels. And the Redenbacher popcorn is using a more 'premium' kernel than the cheap versions.

There's also stuff like time on shelf, moisture content, etc, but I'd bet a lot of it - especially the difference in size and texture - come down to Redenbacher using a different type of kernel, and from a higher-quality kernel within that range.