What distinguishes unequal polyphony from equal polyphony?

The distinction between unequal polyphony and equal polyphony primarily lies in the prominence assigned to different melodic lines within a musical piece. In unequal polyphony, greater importance is afforded to one or more melodic lines, allowing them to stand out more distinctly against the backdrop of accompanying voices. This creates a hierarchy among the parts, where certain melodies may be featured as primary while others serve a more supportive role.

In contrast, equal polyphony treats all voices with the same level of importance, resulting in a more balanced texture where no single melodic line dominates. This type of writing typically showcases interweaving lines that have similar weight and significance throughout the composition. Thus, the absence of a defined hierarchy marks the key difference in texture between the two forms of polyphony.

The other options do not accurately capture the essence of unequal polyphony. For instance, when all voices play the same note, it describes a homophonic texture rather than a polyphonic approach. Similarly, all voices improvising equally is more characteristic of certain styles of music that emphasize collective spontaneity rather than the structured interplay of distinct melodic lines found in polyphony.