Most Champagne is now produced Brut, which means it is dry. Extra Dry, paradoxically, is sweeter, and Demi-sec is sweeter still, and is mainly considered a dessert Champagne.
Unlike the majority of vintage-specific table wines, most Champagne is a blend of different vintages, or nonvintage. This allows each winery to create a "house style" which typically remains the same year after year regardless of individual vintage conditions.
In the best vintages, most wineries produce a vintage bottling, which is considered their reserve or top-of-the-line product, often with its own individual honorary name and a higher price tag to match. These are almost always made in the Brut style.
Blanc de Blancs means that it is 100% white varietal (Chardonnay). Blanc de Noirs is 100% black varietals (Pinot Noir and/or Pinot Meunier).