Here's the quick easy distinction;
Ionic bond: metal-nonmetal
Covalent bond: nonmetal-nonmetal
Metallic bond: metal-metal
The actual distinction has to do with the difference in the electronegativites of the bonding atoms, i.e., how strong their attraction for the shared electrons is relative to each other. This distinction creates some combinations that would fall outside of the above rules, but they are generally usable, in the absence of a table of electronegativites. hope this helps.