What are the differences between playing in 12/8 time signature and 4/4 time signature?

The main difference between playing in 12/8 and 4/4 time signatures is the way the beats are grouped. In 12/8, there are 12 eighth notes in a measure, grouped into four sets of three. This creates a compound feel with a strong emphasis on the first beat of each group of three. In contrast, 4/4 time signature has four quarter notes in a measure, with a more straightforward feel where each beat is emphasized equally.