LED power supply is needed for LED to be work correctly. There are mainly two types: constant voltage and constant current.
With Constant Voltage power supply there is voltage that remains, and current is adjustable automatically until it reaches the peak value. This is the most commonly used with LED strips. Symbol for this type is CV (Constant Voltage)
With Constant Current power supply there is current that remains, and voltage is adjustable automatically until it reaches the peak value. This is used when there is a large amount of LEDs. In this case current limiting can be done in power supply and there is no need for extra components for every LED. Symbol for this type is CC (Constant Current)
These two types cannot be replaced with each other.