A conventional compressor has one speed: it runs flat out until the controller is satisfied, then stops. An inverter compressor uses a drive board that converts the incoming supply and feeds the motor at a variable frequency. When the cabinet is warm or the doors are opened often, it speeds up; once the temperature settles, it slows down and keeps running gently.
This gives tighter temperature control, fewer start-stop cycles and usually lower energy use over a day, because the compressor spends long periods at efficient part load. Inverter compressors also start softly, with a much lower inrush current than a fixed-speed compressor, which helps where a generator or battery inverter supports the shop during power cuts.
The trade-off is electronics. The drive board must cope with Indian supply conditions, including sags, spikes and dust. A surge protector and sound earthing are worth having, and repairs may need the specific board rather than a generic part. For a bakery showcase or a pharmacy refrigerator where steady temperature matters, the benefit is usually worth it.