I don't think there is usually that much difference. A 200 amp fused 240 volt disconnect is in the same ballpark price as a 200 amp 600 volt disconnect, but if you are applying 480 volts instead of 240 you are getting the bargain because to power the same amount of capacity at 240 you would need the more expensive 400 amp switch, then comes the need for larger conductors, contactors, and other gear.
First if talking panelboards, you don't really see pre-configured "load centers" like you see in the miniature breaker series panels in the over 240 volt lines. You have to specify everything you want and "build" your panel when you order it. There is no automatic ground fault protection included, it must be specified. Ground fault protection is not required on less than 1000 amps either. When it is required it usually only need be on the incoming supply which can either be in or ahead of the equipment in question. BTW it is Ground Fault Protection you are talking about and not Ground Fault Circuit Interrupter.
Many equipment out there operating at 480 volts is using gear rated for up to 600 volts. Some gear only has two rating choices, 240 volts or 600 volts.
Common device ratings are 120/240, 240, 277, 277/480, 480, and 600. The ratings are based upon L-G voltage and the prices go up for each.
Then the panels are built based upon L-L and L-G insulation. They also must be braced for their with stand or SCCR.
A 240 panel may identical to a 480 or 600v panel except for some adds added insulation that is included in the 480 and 600v panels. It my be limited to some insulting sleeves slid over some bus connection. But basic bus supports may be identical and the labels are different.
Beyond how the panel is built is the devices themselves.
Is a panel that has all 277/480 or 480v rated devices nameplated 600v?
The panels have to be built to support the devices electrically that will be mounted in then. A panel that has 277/480v devices could be fitted with 480 or 600v devices which is possible but the panel is still labeled 277/480.
As far as pricing goes it may be a matter of functional pricing. A product labeled 240v very well could be the exact same thing as a 480v device except for the label. A 480v device may be identical as A 600v device. Functional pricing in very common.
More expensive doesn't imply that it is actually built better as it may be just the label. In manufacturing these products are it is after more const effective to make products the same but label them diffent because of the added cost of parts and the changes in the manufacturing processes doesn't justify messing around make two entirely different products. It used to be that a simple terminal detail on a device which determined the L-L clearance dictated if the device was either 240 or 480v. When I discovered that I couldn't believe how petty that was. The addition cost of manufacturing 2 different parts and inventory wasn't justified just to collect some extra money for 480v device over a 240v device. But that's was the philosophy in the 1950s -1980s.
As such there is all sorts of stuff going out there but the nameplate on the device is a driving factor.
Also, if a panel has 600v nameplate and rated as such yes, 480v devices can be mounted is it. As such is it a 480v or 600v panel?
