PWM = Pulse Width Modulation of a Voltage Source Inverter (VSI), which is what all low voltage drives use now. Any drive can be programmed to control any motor. PWM drives are around 97% efficient. PWM can however cause voltage spikes that can damage the insulation, hence needing different insulation voltage ratings.
VVI = Variable Voltage Inverter, also known as a "6-Step Inverter", a technology that pre-dates PWM control and ceased to exist in the marketplace once PWM came along because it was not as good, needed "matching" to the motor, and the drives were physically larger and only about 90% efficient. VVI drives also caused more motor heating, so motors had to be over sized (or de-rated, however you want to look at it).
CSI = Current Source Inverter, another old technology that was supplanted by PWM drives for low voltage (still used in Medium Voltage though). A CSI drive controlled the current going to the motor, the voltage was allowed to be whatever it needed to be. CSI drives were hell for stout because they were built with thyristors instead of "dainty" little transistors and used reactors instead of capacitors on the DC bus. But they too needed to be impedance matched to the motor it controlled, so when you swapped out a motor, someone had to come out and add burden resistors to the drive to tune it to the motor. Once PWM came along that allowed any drive to work on any motor, CSI fell by the wayside. CSI drives were were super easy on motors, however often less than 90% efficient. Modern versions that are used on MV motors are now using CSI-PWM, so the motor matching is no longer an issue, and the efficiency has improved to be the same as PWM - VSI. But they have size / power and voltage limitations compared to PWM.