[Closed] Clip-in shoes. What's the difference?

Hi,

I'm considering on purchasing some clip-in shoes for the first time. My first pair is probably going to be a relatively cheap pair, to see if i enjoy them before splashing out on something expensive.

So my question is....

What should i be looking for? Any certain features and/or technologies/designs?

Apart from build quality, is there much difference in them between prices? So if i spent an extra £10-£20, would i actually see a difference?

Also what is the difference between MTB and road clip-in shoes? I've noticed the obvious thread difference but is there anything else?

Cheers for any help in advance.