France is easiest to distinguish by the language, which is not usually hard to spot. France also has lots of French cars (Renault, Peugeot, Citroen), and plenty of very old-looking buildings. Look out for the yellow D-road signs, although don't expect the number to tell you where in France you are.
Plates
Most plates are the regular EU-style plates with just a single blue strip on the left, but double blue is not uncommon. Pre-2009 french plates may be yellow with the EU strip. After 2009, many plates are white with a thin blue strip on the right-hand side. Behind the blur this right-hand strip can appear to be a lighter shade of blue than the strip on the left, which can help to tell it apart from Italy and Albania.
