resumeIn brief
The fuel supply location distinguishes port from direct injection.
Useful to know
In petrol port injection, the PFI nozzle feeds fuel into the intake tract in front of the intake valve. Bosch describes the formation of the air-fuel mixture prior to its entry into the combustion chamber. This differs from direct injection into the chamber itself. [1]
The word "injection" by itself does not specify this difference. When considering a scheme, the most useful question is where the nozzle output relative to the valve and cylinder is located.
The injection site influences the design of the system, but does not allow for a universal rating of reliability and consumption in itself. The specific engine, control and mode matter. Do not choose a cleaning procedure or a replacement nozzle only by the general abbreviation: performance, compatibility and manufacturer's directions remain determinative.
Sources
For further detail and to check the information: