Hi there,
The throttles at cruise are at less than 50% power, depending on altitude and air temperature.For take-off, all jets use a reduced power setting, depending on actual weight and air temperature/density and runway length. A typical A320 power setting for take-off would be about 86%, ie, there is no need to use more than that power setting to get off at the appropriate speed, considering the above factors.Once the aircraft has rotated and climbed, the pilots follow what is known as the flap schedule, to decide when to bring in the flaps/slats, such as reducing to climb power at 1500 feet, pitching down to maintain 190 knots and bring in the first stage of flap, ie, from Flap 5 to Flap 1 and then, at 3000 feet, flap 1 to zero along with a pitchdown to maintain 210 knots.
The A320 has a slightly different fan to the 737-800, which is why there is a slight noise difference.The core engines are pretty much the same.
regards
GttC