Money supply control vs. interest rate control
I think that with money supply control the central bank actively influences The money supply by adding or withdrawing money. By setting the interestrates the central bank influences the lendingcapacity of the banks and the people, lowering the interestrate creates more lendingcapacity and thus 'adds' to the moneysupply... By setting interest rates higher it diminishes lending capacity and thus 'tightens' the money supply..