If you buy your tobacco from a reputable place there isn't much difference at all. The blender and manufacturer have the control over what you're getting.
Ohhh brother you are starting a conversation a fear will go on for pages. Can someone pass the popcorn ?!I am curious: are there tobacco brands that are known for sourcing higher quality tobacco? Or is it basically the same quality across brands and the difference is in how they treat it/blend it/etc?
It also might be that you prefer the component ratios and flavorings that the blender chose in that blend. All blenders are not created equal.However, whether the blend is an English, a burley or perhaps a straight Virginia, the types of leaf used may be the same, but some blends are simply better. I attribute this to a better grade of tobacco being used.
The biggest factor is WHERE its grown. The soil, the water and the sun all have a part in how well your tobacco grows as far as flavor.
The harvesting, drying and curing has been perfected over the years to be almost seamless.
Granted that this is very subjective, but I do believe there is a qualitative difference. It seems different blends that are attempting the same flavor profile may differ because the quality of the leaf used is different.It also might be that you prefer the component ratios and flavorings that the blender chose in that blend. All blenders are not created equal.