What are the differences between 6/4 and 6/8 time signatures in music?

The main difference between 6/4 and 6/8 time signatures in music is how the beats are grouped. In 6/4, there are 6 beats per measure, each quarter note receives one beat, and the beats are grouped into two sets of three. In 6/8, there are also 6 beats per measure, but each eighth note receives one beat, and the beats are grouped into two sets of three eighth notes. This results in a different feel and emphasis on the beats in the music.