its water to air cooling as opposed to air to air cooling. Theres a secondary radiator & pump setup that pumps cooling water through the charge cooler (see the two pipes leading into the charge cooler). Water flows around the pressurised hot air in the cooler as air would in an intercooler, cooling the charge air down.
Adavatages being its more compact, meaning less of a faff to fit and in turn you get less pressure drop with the smaller core required.
disadvantages being its relatively complicated. more expensive, and they heatsoak badly over long periods of user. Good for dragstrip / dyno bragging though as you can pack the rad with ice to massively temporarily lower inlet temps.
