Another interesting contrast to polyphony is heterophony, or heterophonic texture.
This is the kind of sound where you have two voices (or more) doing a simultaneous variation on a melody line.
This is much more common in Asian music, especially Japanese Gagaku and traditional Thai and Filipino music, but some Western composers do make use of it.
However, it's so rarely used that heterophony sounds "weird" to most Westerners when they first hear it.
I will say, heterophony is certainly an acquired taste, but one well worth cultivating.