Use the circuit shown.
Turn the potentiometer P1, until a voltage of approx. Vin = 3.00 V applies to the base. At the same time you measure at the output a typical value of approx. Vout = 2.30 V.
Turn P1 a little further until a voltage of approx. Vin = 4.00 V applies to the base. Now you measure a typical value of approx. Vout = 3.30 V at the output.
A change of 0.01 V at the base results in an equal change of 1.00 V at the output. The output voltage follows the input voltage! Therefore, one speaks of an emitter follower circuit.
The voltage gain of a common collector circuit is 1.
Since the current, but not the voltage is amplified, it can be stated...
The power gain of a common collector circuit is equal to the current gain.
Now you compare these results to a common base circuit...?