Fill Light & Brightness.. are present when photo was last edited using a legacy process version (2003 or 2010).
Shadows & Highlights.. are present when photo was last edited using current process version: 2012.
To switch process versions: use the camera calibration section in develop module (at the bottom), or if you want to go legacy -> current, just click the lightning bolt under the histogram, or use the Settings menu: Update to Current Process Version (2012).
PS - new photos are always current process version, unless you apply a preset upon import to change that.., but old photos stay whatever they were forever, or until you change them - thus the reason why some are one process version, and some are another process version..