What is the difference between Qualcomm QC4.0 and QC3.0?

QC3.0 is Qualcomm's new generation of fast charging technology, one of the Snapdragon 820 processors can be black, compared with the previous generation of fast charging 2.0 faster than 20%.
According to related technical documents,  Quick Charge 3.0   can charge a typical mobile phone from zero to 80% in about 35 minutes. A traditional mobile terminal without Quick Charge usually takes about one and a half hours.

Specific details:

1. Improve fast charging speed by up to 27% or reduce power loss by up to 45% compared to Quick Charge 2.0.

2. 2 times faster charging speed than Quick Charge 1.0.

For charging voltage, Quick Charge 2.0 offers 5V, 9V, 12V and 20V four-speed charging voltages, while Quick Charge 3.0 is available in 200mV increments, offering flexible options from 3.6V to 20V. This will allow the phone to get the right voltage to the desired charge current, minimizing power loss, improving charging efficiency and improving thermal performance.

In addition, Quick Charge 3.0 is backwards and backwards compatible with pre-Quick Charge versions and chargers (including USB Type-C), and has the same ultra-fast charging speed and independent circuitry for OEMs to offer more flexible options. There are also UL certifications that help to meet quality and safety standards.
QC4.0: Increase power to 28W again and add USB PD support. Cancel the 12V voltage file, 5V can output 5.6A, 9V can output 3A, and the voltage file continues to be subdivided into 20mV.