I'm doing an Arduino Uno project and I need to control some motors using my mobile phone through bluetooth. I contacted an Arduino reseller in my country and he said that he has bluetooth shield for $16 and bluetooth module for $40, I don't know which one to buy.
To make things even more confusing, this guy has done something similar to what I wanted to do using this which is only around $6.
But I've also seen other projects that are done using the shield, so what to buy? I don't really care about the price, I am willing to pay, but I don't know which one to buy.
At first I thought that Arduino bluetooth shield is a shield (cover) that protects the module but this guy was able to connect Arduino using the shield only.
My questions are: what is the difference between the shield and the module? What are the differences between different Arduino bluetooth modules? What do you usually buy to connect an android device to Arduino using bluetooth?