Someone else might correct me on this, but I'd say no, there aren't. Since bourbon is by law mostly corn mash they all taste similar, and not vaguely. I think the general rule with imbibing alcohol of any sort is go with the best you can afford. Sure, someone might say using top shelf to make eggnog is a waste, but how? Just because you're mixing it with cream, egg, and sugar you should suffer low quality alcohol? That line of thinking doesn't make sense to me. It's like cooking with wine: use a bottle you would drink, not cheap cooking wine.
That said, for a mid-tier bourbon with no added impurities I recommend Bulleit bourbon.
Ehhhhh, kind of. "Mostly corn mash" just means 51% corn mash, but the remaining 49% makes a lot of difference. That said, it's similar to scotch in a way, since single-malts will be 100% barley, but the difference in taste comes from the strain of barley, the degree of malting, whether it's roasted and to what stage, whether it's smoked and by what, what temperature it's mashed at and for how long, the yeast used to ferment it, the type and material of still, how many distillations it goes through, the cuts made to heads and tails during final distillation, the grade of "toast" on the inside of the barrel, and how long it's aged. A lot can change based on temperature and humidity as well while aging is taking place.
There's a lot that goes into it, and it means that every "recipe" won't yield the same stuff, which is why before bottling several barrels are blended together to make a uniform taste.
