Different varieties of barley are used for barley tea and for whiskey/beer. This nice illustration shows the difference. Six-row barley on the right is used for barley tea and two-row barley on the left is used for whiskey/beer. The two row barley has lower protein and higher carbohydrate content and therefore is more suitable for fermentation. However for some varieties of both whiskey and beer, six-row barleys are used. ニッカ
Photo is a web capture for explanatory purposes, copyright belongs to the company.