The softball swing is entirely different from the baseball swing. In a proper softball swing, the weight is more or less similar to the weight shifting back which is then being forward at the contact point.
There are a bit of knee bending with the leveled swing and the front leg makes the burly finish.
The major difference in the hitting techniques of both games is due to the ball size and pitching difference.
In Softball, the ball is bigger and pitches at the closer distance as in baseball. Also, due to the underhand position, it remains flat.