We usually connect the 3 phase supply in star and delta pattern. What is the benefit by doing so?

For a given volume(space,iron core) 3phase generator will generate more power than a single phase generator as the winding will be evenly distributed than in single motors. Similarly 3ph motor will give more output
Than a 1ph motor. Torque produced by 3ph motor will be more even and it will start or reverse direction of rotation easily than 1ph motor.