Standing orders are distinct from direct debits; both are methods of setting up repeated transfers of money from one account to another, but they operate in different ways. The fundamental difference is that standing orders send payments arranged by the payer, while direct debits are specified and collected by the payee.

• A standing order can only be set up and modified by the payer, and is for amounts specified by the payer to be paid at specified times (usually a fixed amount at a specified interval). The amount can be paid into any bank account, which need not belong to an organisation vetted by the payer's bank.
• A direct debit requires the payer to instruct the bank to honour direct debit requests from a specified payee; the payee can then take a direct debit for any amount at any time. The payer has no direct control over these payments, but can cancel the direct debit at any time, with no reason required, and require the return of disputed payments. It is not possible to authorise an individual to take direct debits; only organisations that have a contract with the payer's bank, or have been vetted by it, can do this.

http://en.wikipedia.org/wiki/Standing_order_(banking)