What is the LOGIC for price comparison site

What is the LOGIC to make price comparison site like http://www.shopping .com
How can we upload single CSV for different category products with different properties and attributes, please help me if ANYBODY can.

EX: for **computer monitors **have properties like
Technical Features (Form Factor,Digital Video,esolutions supported,…) ,
Dimensions (Width ,Depth ,Height, Weight),…

But for camcoders have properties like
Memory Photography (Memory Card Type ,Digital Still Shot Mode,MPEG Movie Mode,…) ,
Interfaces (Output Interfaces,Input Interfaces,Microphone Type),
Power Supply (Battery Type,Battery Life),…

How can we insert these different types of products.

I want to know how is the shopping.com works.

waiting for replay…thanks .