Is wine a part of impurities like urine and stool? For example, if a carpet is stained with a drop of wine, is it considered impure?

According to the majority of the scholars wine/alcohol is regarded as clean. So when a drop of it falls on the clothes, it will still be clean. So in short, its ruling is different from urine and stool. [1]

Reference:

[1] http://islamqa.info/en/148690