Dry is not the same as dry. Different terms for indicating the flavour of wine and sparkling wine are valid. The same term for wine and sparkling wine stands for different contents of residual sugar.
A distinction is made between four flavours of wine.

Dry

is the denotation for wines that are almost fully or fully fermented, i.e. for wines with a residual sugar content of not more than 4 grammes per litre. Moreover, the legislation allows the denotation dry up to a residual sugar content of 9 grammes if the total acidity expressed in g/l is maximally 2 g/l lower than the residual sugar content (formula: acidity + 2 up to the limit of 9). A dry wine is not the same as acid wine. It just contains a small amount of unfermented sugar. However, it is more likely that a higher amount of acidity is tasted more easily in dry wines. 

Medium dry

wines may have 12 grammes of residual sugar per litre and/or up to 18 g/l if the residual sugar content does not exceed the acid content by more than 10 g. (Formula: acidity + 10 up to the limit of 18).

Sweet wines

display a residual sugar content which exceeds the values determined for medium dry wines but does not reach more than 45 g/l.
The indication sweet is permitted from 45 g/l onwards.

A distinction is made between seven flavours of sparkling wine.

The following guidelines have been valid since 1 August 2009 (EU Regulation 606/2009) for the different kinds of flavour (dosages):

• 0 to 3 g/l: brut nature (German: “naturherb”)
• 0 to 6 g/l: extra brut (German: “extra herb”)
• 0 to 12 g/l: brut (German: “herb”)
• 12 to 17 g/l: extra dry (German: “extra trocken”)
• 17 to 32 g/l: dry (German: “trocken”)
• 32 to 50 g/l: medium dry, demi-sec (German: “halbtrocken”)
• Above 50 g/l: sweet, doux (German: “mild”)

(Source: German Wine Institute, www.deutscheweine.de as of 5 July 2011)