b) distinction between actual and potential growth

• what's Actual economic growth ?

  an increase in quantity of goods/services produced in an economy in a given period of time
• how's actual growth measured?

  by percentage change in real gross domestic product (GDP)
• what's Potential growth?

  increase in productive potential of an economy 
• how's potential growth shown?

  shift outward of the PPF or LRAS curve
• actual economic growth may be less than the potential growth available to the economy