In Germany, the main language spoken is German. One fun regional difference is that in the north of Germany, it is more common to use Moin (Hello) as a greeting. In the Czech Republic, Czech is the main language spoken. Czech is a West Slavic language with similarities to Polish and Russian.
In Germany, the Euro is used and in the Czech Republic, the Koruna is used. This is unique because only a few countries in the European Union do not use the Euro. 1 Euro is worth 1.07 US dollars and 1 Koruna is worth about .045 US dollars. This means it is very common to carry around 100 or 200 Koruna bills in the Czech Republic.
In Germany, a liter of water would cost about .85 EUR. In the Czech Republic, the same amount of water would cost you about 22 Koruna or .92 Euros. Fun Fact: Many Germans prefer to drink sparkling water over "still" water without bubbles in it. If you were to order water at a restaurant, it would be common to receive sparkling water if you didn't specifically ask for still water.
