Save, preserve, conserve can mean to keep free or secure from injury, decay, destruction, or loss.
Save may imply measures taken to protect something from danger of loss, injury, or destruction, but, more often, it suggests rescue or delivery from a dangerous situation (see under RESCUE ) .
Preserve stresses the idea of resistance to destructive agencies and hence implies the use of means to keep something in existence or intact.
Conserve, on the other hand, suggests keeping sound and unimpaired and implies the use of means to prevent unnecessary or excessive change, loss, or depletion.