The power coming from the grid is always AC power, and this gets converted to DC. IN case of everyday household items (such as a phone charger) the conversion to DC happens in the plug. In case of electric vehicle the conversion happens in the car itself. This results in longer charging sessions, also because the charging power is typically of a lower capacity. These type of chargers are ideal for locations where clients and guests stay for a longer period of time, such as hotels, workplaces, conference centers or restaurants.
In case of fast, DC charging the conversion from AC to DC happens in the transformator of the charging station itself. As the power is converted before it enters the car it bypasses the car's onboard charger and gets stored in the battery directly. Due to the technology and the power required from the grid DC chargers are much robuster and more expensive. On the other hand the charging sessions are a lot quicker and efficienter than charging with AC. This makes high-power fast chargers extremely suitable for locations where the drivers don't intend to stay longer, such as tankstation, fast-food restaurants, supermarkets or strategically well located points along transport corridors.