In organic compounds carbon displays different oxidation states. One can thus transform a functional group into another by either reduction or oxidation.
Depending where we are in the 'redox tree' and where we want to go to, we would use either a reduction or an oxidation
The reduction of aldehydes and ketones can be accomplished in two different ways:
Can you say anything about the 'selectivity' of the two hydrides? Which one is more 'selective'?