@bharat:
The health and life condition of the hard drive.
It shows the percentage of the remaining health and life of your hard drive. A perfect disk (though there are no such disks as there are no perfect people
would have 100%. As the disk works and becomes “worn out”, the level decreases. As in other visual elements, the green color means that everything is all right, yellow means an urgent state, and red means that the state is critical and the disk must be immediately replaced.
The performance level of the hard drive.
It estimates the overall performance of the hard drive based on some of its technical parameters. Mind that this parameter concerns the hard drive only and the total performance rate depends on your computer. Use this parameter rather as an informational means.
Source : Taken from the HDDLife FAQ. (Help menu).