Re: vegetable glycerin
We regard vegetables as cleaner and healthier than something which is an "animal byproduct," a term that is loathsome for most Western sensibilities. However, what you are describing is purely perceptual. The term "glycol" defines a specific chemical compound; if there were to be any difference, even if it were a difference of just one element, it would no longer be glycol at all. Therefore, glycol is glycol is glycol.
It's a moot point anyway, since as I stated it doesn't appear animals are commonly used as a source for the compound anymore in light of the abundance of waste glycol thanks to biodiesel. That option is both cheaper and appeals to our love for cute, fuzzy things; there would be no reason to use animal-derived glycol. I would expect a container that says "glycerine" on it and a container that says "vegetable glycerine" on it to contain glycol from the same source.