what is the difference between an I-pad, PDA and a I-pod and a smart phone?

[mary]

i am quite confused. so far i only use an i-phone .

 

[Suman'Sam']

An iPad is a Bigger iPod Touch and an iPod Touch is an iPhone without Calling Facility.

Smartphone is a mobile phone which can do much more just "calling", iPhone, Android, Windows Phone and BlackBerry are all included in this category.