Halachic authorities rule that very similar products, such as different brands of Corn Flakes, have different blessings. See, e.g., Rabbi Dovid Haber, writing for the Star-K, and citing Rav Moshe Feinstein, z"l:
Rav Moshe Feinstein, zt’l,20 explains if the grain has not been ground down to flour, but only popped (e.g., popcorn, or the grit is rolled into corn flakes), it retains its Hoadama status. Kellogg’s Corn Flakes and Frosted Flakes cereal are made from recognizable corn pieces (called grits) that are not ground into flour, so the brocha is Hoadama. However, Kemach Brand Corn Flakes is made from corn flour; therefore, its brocha is Shehakol. The same is true regarding Corn Chex; therefore, the brocha is Shehakol.21
If a corn flake cereal is not on the brochos list, how can one tell if the brocha is Hoadama or Shehakol? If the cereal lists corn flour, the corn has been ground and reformed into pellets so the brocha is Shehakol (if wheat and oat flour are not present). If the cereal lists corn or milled corn, it may be a whole grain product and the brocha is Hoadama, or it may be ground and the brocha is Shehakol. To determine the brocha, one must look carefully at various flakes. If they have jagged edges, the surface of the flake is bumpy, it comes from a grit22 and the brocha is Hoadama. If the corn flakes are relatively smooth (very small bumps), and the edges are smoother, the corn flakes are from a more uniform pellet (made from corn flour) and the brocha is Shehakol.
The corn flake on the left is Shehakol because it is made from flour that is reshaped into uniform pellets. Note the smooth edges. The corn flake on the right is Hoadama, as it is made from corn grits. Note the jagged edges – especially on the upper-right hand side. Also, note the bumpier surface.
Kellogg’s Corn Pops is manufactured differently in various facilities worldwide. In the United States, the corn is not ground into flour, and corn pieces are used; therefore, the brocha is Hoadama.
Choveres Torah V’horaah 5733.
It is interesting to note that the “corn” in Corn Chex is different than the corn in Crispix cereal (despite the fact that the finished product looks similar). In Corn Chex, the corn used is no longer nikker (noticeable as corn), and in Crispix it is still nikker; hence, the difference in brocha.
The shape of the natural grit is not as uniform or smooth as a manufactured pellet; hence, the rougher edges and bumps.
I am having some trouble understanding the reasoning behind this distinction and was unable to locate the article by Rav Moshe to see if he explains it further. Why would the relative identifiability ("nikker" - "noticeable as corn") at an intermediate stage of production be relevant to whether the final product is identifiably corn? Is the idea that an expert would even be able to detect the identity of the final product, even if a layperson would not?