I'm little bit confused. Help me please to make everything clear. I want to buy oscilloscope and found two models suitable for me.

1. Rigol DS1102E
2. Rigol DS1102CA

But I don't understand the difference between them. I read that DS1102E has 1 GSa/s sampling rate and DS1102CA has 2GSa/s. OK. But what it gives in practice? Both oscilloscopes have a bandwidth of 100MHz, so I won't find a difference in picture of signals on screen. Am I right? So could you explain me what is the meaning of 'sampling rate' and 'bandwidth' for modern oscilloscopes? And what is the difference between these things?