The grain can influence flavor a lot, but that's more from how the grain was processed than where it was grown. I don't think I could tell American 2-row pale malt from British 2-row pale malt or Belgian pilsner malt, but they'll both be pretty different from Vienna malt, which is kilned darker. Small additions of "specialty" malts like roasted barley or various caramelized malts can also shift flavor quite a bit.