rolling plan vs big bundle plans explain

[LooBerry]

Hi I am on the £10 big bundle which auto tops up each month taking £10 each month from my bank account to restart a new month allowance and i was thinking of changing to the £10 rollover plan. But reading the details I can't see the difference between the two plans. Correct me if i'm wrong but both take £10 each month from your bank 2 days before the topup with your new allowance, but both give unlimited texts, unlimited calls and 8GB data. As I don't use all my data allowance each month, whats the benefits between the plans. can anyone explain simply what is the difference.  

[MI5 · Accepted solution]

@LooBerry 

The only difference is that you have the choice to top up or not on a bundle but on a rolling plan you agree to pay every month by a continuous payment authority.

Rolling plans are essentially a 30 day contract for people with poor credit ratings.

[Oxonian]

@LooBerry 

Another slight difference is that you do not have to top-up every month on the Big Bundle. That renews monthly if you have sufficient credit on your PAYG "account" so you could do one top-up of £50 and then forget about it ; your Big Bundle will renew for the next five months.