Wheat are brewed with a significant portion of wheat.  There are two major types of wheat beers.  The first type is witbier which is a Belgian style, and the second type is weissebier which is a German style.  Witbier and Weissebier both translate to "white beers" in Belgium and Germany.  The name comes from the lighter, cloudier look of wheat beers.  Since the beers are not actually white in color, the term is relative, similiar to "white wine".   

There are two different types of German wheat beers, which are the Bavarian Wheat beer and the Berliner wheat beer.  The Berliner wheat beer is very low in alcohol and is tart.  Sweetened syrups are often added to the beer before consumption.  There are different types within the Bavarian style which include the Hefeweizen, the Kristalweizen, the Dunkelweizen, and the Weizenbock.  The Dunkelweizen and the Weizenbock are darker wheat versions.     

Hefe = yeast
Weizen = wheat
Weisse = white  

Hefeweizen refers to wheat beer in its traditional, unfiltered form.  Hefeweizens are usually straw colored and contain flavors of bananas, cloves and occasionally citrus. 

Kristallweizen refers to a wheat beer that is filtered to remove the yeast from suspension.  Kristallweizens have bright and clear bodies from pale straw to light amber. Flavors will be more clean and softer on the palate, and the common banana flavoring will be lighter.

The dark wheat varieties typically have a much higher alcohol content than their lighter cousins.  Dunkelweizens are  are brewed as darker versions (Dunkel means "dark") and usually brown and cloudy from the yeast.  They are brewed   with complex malts and a light sweetness with low levels of bitterness. The common wheat and banana flavors are also present in this style.

Weizenbocks ("bock wheat") are more powerful Dunkelweizens with the same dark color.  The bodies usually have hints of alcohol, spiciness, rich, dark malts and dark fruits.