IPhone 4 vs iPhone 4S vs 5 vs 5s camera?

What is the difference?

They gette "better" with each newer iPhone. I have a 5s and in the day it takes great pictures, but its not too good at night, even with flash they come out kinda bad. All the other iphones arent as good as this one though since they are older models.

5S is by far the best and includes stuff like burst mode, slomotion video, low light video, faster lens, etc

Better is a relative term when it comes to phone cameras. They are All very limited in their ability to deliver true quality, controlled, consistent photography due in large part to the tiny sensor and poor lens. Even a very basic, MUCH lower cost point and shoot camera can give better results. You could easily buy a nice DSLR for what you are spending on those phones.

You can, for instance, get far better photos with this $69 camera than you will get with ANY iPhone:
http://www.bhphotovideo.com/...amera.html

It doesn't matter. Phone cameras will never be comparable to dSLRs and point & shoots. I have an iPhone 5 and I rarely use the camera. If you're used to shooting with a dSLR, no phone camera can satisfy you.