Quoted from Qualcomm:
Quick Charge 1.0 is able to charge up to 40% faster than conventional charging.
Quick Charge 2.0 increases the charge time advantage up to 75%, as well as introducing an array of compatible accessories including wall adapters, car adapters, and power banks.
Quick Charge 3.0 is engineered to refuel devices up to four times faster than conventional charging. It is designed to charge twice as fast as Quick Charge 1.0 and to be 38 percent more efficient than Quick Charge 2.0. Now consumers can spend even less time charging, and can grab and go more quickly.
Quick Charge 3.0 employs Intelligent Negotiation for Optimum Voltage (INOV), an algorithm which allows your portable device to determine what power level to request at any point in time, enabling optimum power transfer while maximizing efficiency. It also supports wider voltage options, allowing a mobile device to dynamically adjust to the ideal voltage level supported by that specific device. Specifically, Quick Charge 3.0 offers a more granular range of voltages: 200mV increments, from 3.6V to 20V. That way your phone can target one of dozens of power levels.
Quick Charge 3.0 is 100 percent backward-compatible with Quick Charge 1.0 and Quick Charge 2.0 devices, and it supports a broad range of connectors: Quick Charge 3.0 can be implemented with USB Type-A, USB micro, USB Type-C, or proprietary connectors.