What is the difference in the capability and usage between the zero cross (ZC) type and non-zero cross (NZC) type phototriac couplers?

There are two types of phototriac couplers; ZC and NZC.

The ZC type can turn on an AC load voltage near zero, allowing you to minimize switching noise. It is suitable for the circuits adversely affected by noise, but not capable of providing phase control.

On the other hand, the NZC type can turn on a load voltage at any desired timing, allowing phase control such as adjusting the motor rpm and heater temperature. Depending on the load condition, however, there may instantaneously occur a high current (noise).