RFID uses radio waves to read the data in RF tags. The higher the bandwidth of the radio waves, the further away the tags can be read. Unlike bar codes, you can read the tags without getting close to them and oftentimes without even seeing them because radio waves go through wooden cabinets, cardboard, clothing, paper, etc.
A barcode is a method of representing data in a visual, machine-readable form.
The lines and spaces in barcodes correspond to numbers and letters which barcode readers or mobile devices with a built-in camera can read.
Image recognition is a technology that identifies objects in pictures and videos. Information gleaned from pictures and videos can be aggregated to a database, and the computer learns as information is added and more time goes by.