How are polyphonic and homophonic textures different from monophonic?
Most of the music we listen to consists of more than a single melodic line. More often we might have several different instruments playing together, each with its bit of melody, or a song that has a chordal accompaniment on piano. We refer to these overall effects as texture.
In the musical sense...
A monophonic texture refers to music with a single melodic line (no harmony or counterpoint) sounding the same thing at the same time—whether played or sung, performed on a single instrument or by a voice or voices and instruments playing in unison. An example of monophony is one person whistling a tune, or a more musical example is the clarinet solo that forms the third movement of Messiaen's Quartet for the End of Time.
A homophonic texture refers to music where there are many notes at once, but all moving in the same rhythm. Homophonic music has one clear melodic line, the part that draws your attention, and all other parts provide accompaniment. A good example is the moment in the "Hallelujah" chorus where the chorus sings a series of "Hallelujahs" in the same rhythm.
A polyphonic texture refers to a web of autonomous melodies, each of which contributes to the texture and the harmony of the piece but is a separate and independent strand in the fabric, so to speak. An example is the section in the "Hallelujah" chorus where the choir sings "And he shall reign for ever and ever." Additionally, Pachelbel's Canon is polyphonic.
Note that most pieces are not all one texture or another. A singer and a guitar, for example, are not exactly homophonic, but close.
You may compare and contrast these explanations to answer your question.
This question is categorized as "physics" but I am unsure which sort of physical explanation might be sought after specifically in terms of musical textures. If this does not answer your question, please be more specific.
I referenced the textbook Music Then and Now by Thomas Forrest Kelly to ensure the accuracy of my answer. See chapter 1, Fundamental Musical Concepts and Forms, "Texture."