• What is the difference between traditional photography and digital photography?

Analogue uses light sensitive film and Digital use light sensor.
Analogue uses negative process and Digital uses Positive Process.
Digital uses no light sensitive paper. 

• What are the different sources of digital images?

The Different Sources are:

Camera,Phone,Laptop,Web-cam,CCTV Cameras and photo scanners they are many more Sources 

• How are digital image files stored and played on a computer?

The storage devices USB, Memory Card, Wifi, bluetooth.

• How is digital image file quality measured

megapixel= equals to 1 megapixel = 1 million