What was the difference between medieval and ancient instruments?

Answer 1

I am assuming you are referring to Musical Instruments.

The middle ages saw the introduction of bowed instruments. There were primitive predecessors of these in ancient times, but they were not important European instruments. This meant that the medieval people had fiddles of all sorts, including hurdy-gurdys, which ancient people did not have.

Medieval music was much more dependent on harps than ancient music was.

There are some indications that ancient people had Bagpipes, and even that Nero played one, but there were probably not common as they were in the Middle Ages.

The Middle Ages saw the introduction of new types of organs that could be moved easily. One of these, the portative organ, was small enough to be carried and played by a single person and were used in processions.

The instruments that were ancestral to the guitar were introduced in the Middle Ages, and they differed from lutes in that they had flat backs. Other instruments called citterns also had flat backs, though their outlines were more like lutes.

The medieval lutes themselves were medieval introductions to Europe from Arabic lands.

In ancient times, there was a lot of use of lyres, which were mostly out of favor in the Middle Ages. (The Byzantine lyra was not a lyre, but a bowed lute.)

Unfortunately we do not know much about ancient musical instruments, so a complete comparison is impossible.