Differences between e5, 891 and 896

Hello, we want to buy a roomba and there are offers with some models in the same price range and I can't find what are the differences among e5, 891 and 896.

There are any major differences? I'm only noticing a better battery life on the 896 (2 hours) and that e5 has iAdapt 2.0 but looks like it doesn't have camera mapping. Can someone help me?