Depending on your application you should distinguish between two different bandwidths:
1) The analog bandwidth of the scope
2) The bandwidth of the ADC according to the sampling frequency
Often people forget to distinguish between them. This bandwidth tells you the highest frequency that can reach your ADC. The cool thing here is, that you then can also sample in higher Nyquist bands. Generally the Nyquist theorem tells you that the highest frequency you can sample without running into aliasing is the half of the scopes sampling frequency. So if the scopes sampling frequency is 100 MHz then you can sample signals up to 50 MHz in theory (you should never reach that point because the filters could already introduce a damping). But if the scopes analog bandwidth e.g. goes up to 300 MHz you can also sample the signal in a higher Nyquist band e.g. second or third Nyquist band. This is interesting depending on your application e.g. avoiding folding products from higher frequencies or to get rid of the trash around DC. The resolution of the ADC in bits is of special interest if you have high dynamics in your signals or if you are going to measure very weak signals. The rule of thumb here is SNR=6.02*Bits+1.76dB. And the mentioned resolution e.g. 8 bits isnt equal to 8 bits. The effective number of bits is always lower than the one mentioned in the data sheet.
Greetz from Germany