Most Champagnes are made from among just three grapes-Chardonnay, Pinot Noir, and Pinot Meunier. Some are made from just one of each. (There may be Champagnes made from just Pinot Meunier but I don’t know of any; many Champagnes are a mixture of juice from two or three.)
However, it’s a little-known fact that there are actually 7 grapes permitted in Champagne: the three above, as well as Pinot Gris (sometimes called Fromenteau), Pinot Blanc, Petit Meslier, and Arbane. And there are a few-very few-Champagne makers who actually do use these grapes, but their bottles are mostly sold on the French domestic market as far as I can tell.
Blanc de Blancs is white Champagne made from 100% Chardonnay. Blancs de Noirs is white Champagne made from Pinot Noir or rarely Pinot Meunier grapes, or often both. There’s little or no color from those red grapes, though, because the juice is gently pressed and then fermented with no skin contact. Sometimes you’ll see a slight hint of gray or pink in these wines.