A.
Skimming refers to looking only for the general or main ideas, and works best with non-fiction (or factual) material.
B.
Skimming is for fast reading while scanning is for a more careful reading.
C.
When scanning, you look only for a specific fact or piece of information without reading everything.
D.
Scanning is reading a text quickly in order to find specific information, e.g. figures or names.