There were several advantages and disadvantages for the Allies and the Germans. The biggest advantage for the Allies was that they had the element of surprise. The disadvantage for the Allies was that even though Hitler took the bait and thought the main attack was elsewhere, they still faced a very large German force where the main attack was launched at Normandy.
The advantages for the Germans is that they had a very strong army and they had armored support. The main disadvantage for the Germans was that they let them selves get fooled by the Allies into thinking they would assault a different beach head and not Normandy.
The advantages for the Germans is that they had a very strong army and they had armored support. The main disadvantage for the Germans was that they let them selves get fooled by the Allies into thinking they would assault a different beach head and not Normandy.