I think one is PUSH the other PULL.
Say I decide to pay one of my children �20 each month. I set up a standing order to send money from my account to theirs.
My children have no control over the money and cannot, for example, alter the amount.
So that is me PUSHING the money from my account to theirs.
If I want to stop the standing order I write to the bank and ask them to stop paying it.
A direct debit allows a company like the Gas Board to PULL money from my account.
Once I sign a direct debit they can take the money out each month, and as long as they let me know, they can change the amount up or down.
And if I want to stop the direct debit I have to write to the Gas Board and ask them to stop doing it, not the bank.
So with a standing order I am in complete control (PUSH), with the Direct Debit I am still in control, but it is the other party who take the money from my account (PULL).