I see that 4 different types of acceleration data can be given by the sensor. What do these mean?

The raw acceleration is taken directly from the accelerometer and converted into units of g. Corrected acceleration is the value of the acceleration once the calibration has been applied. Normalized acceleration is the unit vector of acceleration, and gives only the direction of acceleration (not the magnitude). The corrected linear acceleration in global space takes into account the sensor's orientation, and gives the acceleration acting on the sensor in the global frame rather than the sensor's reference frame. This value is also given in units of g.