What is the difference between a lyre and a Germanic lyre?

Answer 1

Simple, a Germanic lyre was used by the Germanic peoples, a "normal" lyre wasn't.

On a more serious note, it's a completely different instrument. The Greek lyre had many strings that were plucked one at a time, much like a modern harp. The Germanic lyre had usually only 6 strings, and was sometimes played in the above fashion, but more often by strumming while blocking some strings with your fingers to create chords.

Apart from this, they also look quite different. They also come from different cultures: the Germanic lyre was used by the Germanic tribes (obviously) while the classical lyre was used by the Greeks (and other mediterranean cultures).