Some differences between 4-Stroke and 2-Stroke Engines:
4-strokes are quieter
4-strokes get better fuel economy
2-strokes generate more RPM (11,000-13,000 rpm with prop
while 4-strokes rev to around 9,500 rpm)
4-strokes generate much more torque and will swing a larger prop.
4-strokes have a realistic sound similar to a real airplane engine.
(The sound of the engine is lower in pitch than a 2-stroke)