What is the advantage of 480 over 220?

The advantage is more capacity but with less copper, smaller wire, and along with smaller conduits, so less material and labor costs for initial installation.

To illustrate:

The actual voltage for a 3 phase service would be 120/208 volts, so for example, a 400 amp service entrance, would use #500 MCM copper, which will provide a total of 115 KW of power, which includes 80% derating.

A 277/480 volt 400 amp 3 phase service will provide 265 KW of power, with the same size wire, an increase of 230% capacity.

Using 277/480 volts will help with dealing with any distances and help keep voltage drop lower.

You need to look into any new equipment you plan to purchase, to be sure it will be available in 480 volts 3 phase. Most should be.

I have one customer that is a fab shop, and all of their 20 or so welders, of all sizes, and plasma cutters and welders, are all 480 volts, along with air compressors, exhaust fans, cranes, etc.

Any fluorescent and HID lighting can be 277 volts, or HID lighting can be 480 volts. HVAC units can be 480 volts. A smaller 480/120-208 volt transformer and distribution panelboard will be needed in your switchgear package to provide 120 volt power for misc items.

You can do a feasibility/budget study to compare costs of both 208 volt and 480 volt services, along with the costs of your process equipment, lighting, and HVAC. While you may not need the capacity provided by a 480 volt service now, it will also provide future capacity for any expansion of your operation.

While the utility will still only charge for KWH, which will be the same for both voltages and same usage, they may offer an incentive for 480 volt, or better put, a penalty, for providing a 208 volt service, since 480 volt is now much more prevalent for commercial and industrial applications. Include their installation and monthly costs for both services in your budget plan.