Ah, how do you know? Have you done a properly conducted double blind survey?
The Beeb's mini-test did point out that people can tell the difference between different brands, because some are better quality than others - but not between the different styles of the same brand.
I find that Lidl's chunks taste exactly the same as their steaks to me. And all are considerably improved by draining out the food-grade sunflower oil and tipping on (sorry, can't bring myself to 'drizzle') some decent olive oil.
Presumably they mashed the steaks and chunks up until they were the same kind of slurry as the flakes for this test, then? It's the texture, and the fish to oil ratio, that you are paying for.