What is the difference between 220 volts, 3 phase and 380/220 volts, 3 phase (overseas applications)?

380 volts, 3 phase wye (220 volts line to neutral)

If you have 380/220 volts and 3-phase wye power (like most countries), the kiln will come with a 4-wire power block for the 3 hot wires that give 3 phase and one neutral wire.
If you measure between any two hot wires you get 380 volts.
If you measure between any hot wire and neutral you get 220 volts.
The kiln circuits are connected to the neutral line and one of the hot lines for each kiln section to provide 220 volts for each kiln section.
In addition to the 3 hot wires and the neutral wire, an earth ground wire is needed as well.
Some countries have 400 volts with this same basic wye system and get 230 volts from hot to neutral.
Some countries have 415 volts with this same basic wye system and get 240 volts from hot to neutral.

NOTE: All our electrical specifications (shown on each kiln page) show the various electrical specifications for these electrical systems.

If you have 220 volts and 3-phase delta power available, the kiln will come with a 3-wire power block for the 3 hot wires that give the 3-phase.
Between each hot wire, 220 volts can be measured.
There is no need for a neutral wire to come to the kiln in this case, just an earth ground wire in addition to the 3 hot wires.