When the sourcing is categorical, like sunflower oil vs canola oil, there is a difference in the chemical composition of it. ("Oil" is categorical.) Pure table salt is sodium chloride, whereas "sea salt" is mostly sodium chloride, along with a number of sea water-derived contaminants. "When it Rains, it Pours" Morton salt is contaminated with fine silica, to prevent clumping in high humidity. Iodized salt is sodium chloride plus a salt of iodine. "Kosher" salt is merely certified to be just plain old sodium chloride--just like non-iodized, non-Morton table salt.
As for glycerin, its source matters to certain religious prohibitions, even though the final chemical is identical. [e.g. Orthodox rabbinical decisions have ruled that pork-derived insulin is just insulin, and so is therefor kosher, whereas pork-derived insulin is not halal.] I'm sure that some vegans consider the source of glycerin to be important.
Bob