What's in a name? - grape varieties and confusions

Lunel, where we live, is one of several places in France which produces a Muscat vin doux naturel.  We love these sweet, fortified wines and so do many of our friends.  A couple of whom, hoping to take some back home with them, decided to rush into the supermarket on their last day to buy a  bottle.  They emerged with Muscadet (de Sèvres et Maine) - not the same thing at all.  So here are a few notes on some of the confusions in the world of wine and grapes - very personal and not scientific or exhaustive:

• Grapes come in many varieties or cépages each with its characteristic flavour - in some parts of the world it is the grape variety which is highlighted on the label; in France it is usually the appellation - often the place or area of origin - which identifies a wine because French winemakers believe the terroir (a subtle combination of soil, geology and climate) has as much or more influence on the character of a wine.
• Muscat - a fragrant, floral grape used for many sweet and a few dry white wines, in France, Spain and Italy as well as in some countries of the new world.  Muscadet is a variety used in dry white wines from the lower Loire.
• Clairette de Die (from the Drôme département in south-east France) is a delicious sweet sparkling wine made mostly or entirely from the muscat grape, and so with the characteristic floral scent and flavour.  Although the Clairette grape is sometimes used in small quantities with muscat in Clairette de Die, its main use is in the dry sparkling white wine called Crémant de Die.
• The Clairette grape is used in many white wines in the Languedoc in particular, blended with other grape varieties.  But it is also used on its own in two appellations in the region to which it gives its name - Clairette de Bellegarde (Bellegarde is a village south of Nîmes) and Clairette du Languedoc (made in the country area between Montpellier and Pézénas).
• The word clairette comes from the same root as claret, now used by the English-speaking world (but seldom by French people) for red Bordeaux wines.
• Vins doux naturels are certainly sweet but in a sense less 'natural' than other wines - they are slightly fortified (similar alcoholic strength to sherry, for instance) because alcohol is added to stop fermentation before all the sugar in the grapes is converted to alcohol.
• Many famous French appellations are blends of two or more grape varieties, but some are made from single cépages.  Examples: most red and white wines from Bourgogne (Pinot Noir and Chardonnay respectively), northern Rhône wines (reds such as Cornas and Crozes Hermitage and the white wine Condrieu which first made Viognier famous), and red Beaujolais (gamay) as well as most Alsace wines which bear the name of the grape on their labels.
• Red wines get their colour from grape skins, left in contact with the juice for some time.  Many rosés acquire their colour in the same way but with shorter skin contact, although a few are made from grapes with coloured juice.  And since the juice of red grapes is sometimes 'white' it can be used to make white wines - a major example is Champagne, much of which uses Pinot Noir (often belnded with Chardonnay).  Thus Champagne made from Chardonnay alone is called blanc de blancs meaning white wine made from white grapes.