<human>:  What is the difference between a Cabernet Sauvignon and a Merlot wine variety?
<bot>: The primary difference between Cabernet Sauvignon and Merlot wine varieties is the tannin content. Cabernet Sauvignon tends to be more tannic than Merlot, with bolder flavors of blackberry, cassis, and blackcurrant. Merlot, on the other hand, tends to be less tannic with flavors of plum, cherry, and chocolate. Both are commonly used in blends, with Cabernet Sauvignon more likely to be used for structure, and Merlot for balance and body.