ARS-GRIN (USDA Agricultural Research germplasm seed bank) has several thousand tobacco strains on hand, which arrived from many different source countries.
I have grown 8 different Virginias, (in the same geographical location with the same fertilizer), and I could probably have been able to tell them all apart if I could see the leaf, or was not smoking them in blends. One was Russian, two Ukrainian, three American, one Canadian, and one Colombian. The Russian and Ukrainian ones were more similar to each other than the rest. The Canadian tasted like Canadian cigarette tobacco. Whether someone grows the Canadian Virginia Delgold in Canada, New Zealand, or Ohio, it is going to be discernably "Delgold-ish" vs "New Zealand-ish", or "Ohio-ish". This tells me that genetics is an important variable, and offers a reasonable theory why tobaccos with the same name, eg "Virginia", are different from country to country. Its not terroir. They have been changed either by breeding, or genetic drift and poor pollination control.
You see this in action with supposedly "Cuban seed" cigar leaf as well as in the Balkan countries. There are dozens, if not hundreds, of different oriental tobaccos. This probably isn't the result of Portuguese, Dutch, and Spanish explorers and traders bringing an equal number of separate strains to the old world. With all these strains, it's handy to dumb it down with generic terms, but we are missing the big picture. You can clearly tell Bursa, a tobacco from the Marmara region, apart from Izmir which is from from the Izmir region (go figure), because they are altogether different tobaccos.