There are endless items to go over here, so we'll keep it simple and cover what we know most with our 67 years in Agriculture which are Whey & powdered Greens.
Every brand I personally know of who sells whey gets it as a Food grade product. However, they blend & mix X ingredients and are forced to sell it as a supplement.
When supplement ingredients are added, the entire product is then labeled supplement. The #1 supplement added to whey are amino acids. This is simply a marketing strategy to say, "we added this and that makes it better". In actuality, you do not want amino spiked whey because the amino profile in whey is already incredible and the source of the "aminos" will surely never be disclosed giving you a questionable level of "quality" added.
I've been in this industry for over 2 decades, and I have yet to figure out where supplemental amino acids are derived from because no company discloses it. When transparency is low, we can usually guess the reasoning.
When it comes to greens products, it's the same exact thing with different additives. These include supplement sweeteners and/or X ingredients added.
No matter the product, when additives are there which are supplemental, the product is a supplement. You still get a percentage of the food product, but who pays for a percentage?... And, supplements are subject to sales tax, whereas our products never will be as they are Food.
Give plenty, train hard, and eat well!