This seems like it should be obvious. That red wine is made with red grapes and is therefore, red in color. But, sparkling wines (which are certainly not always red) are often made using the lovely red grape, Pinot Noir. So why is red wine red?
White wine and red wine go through different steps in the winemaking process. One of the key differences is that red winemaking includes a “maceration” step whereas white wine does not. After the red wine grapes are crushed, the must (or grape’s juice) is mixed with the grape skins and stems. This is called the “maceration” process. It is the grape skins that give red wine its color (and also help form the tannins in the red wine). In contrast, white wine juice is crushed and pressed from the grape and then kept separate from the skins. When red grapes are used to make non-red colored wine, the grape must is kept separate from the skins, and therefore doesn’t absorb all that dark red color.
Wine Know Side Note: When you buy a sparkling wine that has “Blanc de Noir” on the label, that is a sparkling wine most likely made (in part) with Pinot Noir grapes.
Remember that I Love Lucy episode when Lucy is stomping the grapes with the Italian woman? Stomping of the grapes was sorta like the maceration processes of today. (Though they stopped stomping grapes well before this episode and switched to machines.)
There are a few different methods winemakers can use to macerate grapes. But all in all, it is that step in the winemaking process that is unique to red wines, and ultimately makes red wine red!