What most of us think of as "Virginia" is flue-cured tobacco. When it is air-cured, it takes on a different quality from what you might expect. The differences you noticed may be due to differences in the stalk level from which the leaves were harvested. Lower leaf is thinner, lighter in color, and lower in nicotine. Upper leaf is thicker, darker and stronger.
If you plan on growing a Virginia again, and don't plan on building a flue-curing chamber, then you might consider sun-curing it. The results are not as bright as flue-cured, but brighter than air-cured.
Bob