How to tell the difference between a Iphone 4 and a Iphone 4s?

I have a black Iphone, I'm not shure if it's the 4s or just the 4. How can you tell the different in looks? It also has a bad esn, Is their anyway I would be able to activate the phone?

You can't.

One has an 's" on the end and the other doesn't

IPhone 4s has more megapixels camera and Siri
looks no difference

Look at the top of the iPhone beside the headphone jack. To the right side of the headphone jack if there's a black line its an iPhone 4 if there's nothing it's an iPhone 4S. I get this question all the time being in the iPhone repair trade

Depending on where you are located and the network there are a number of companies that can remove your phone from the block list. Also a ban is usually only in a country so if it was banned in the UK you would still be able to use it in the US.