What is the difference between playing a musical piece in 2/2 time signature versus 4/4 time signature?

The main difference between playing a musical piece in 2/2 time signature and 4/4 time signature is the emphasis on the beats. In 2/2 time signature, there are two beats per measure with a strong emphasis on the first beat, while in 4/4 time signature, there are four beats per measure with a more even emphasis on each beat. This affects the overall feel and rhythm of the music.