Is there a difference between the two?
In addition to the excellent answer from hamrrfan, I would add that concrete is typically much stronger than cement due to the addition of the aggregate.
Cement is the binder that holds the ingredients together in concrete. CEMENT: ...a powder of alumina, silica, lime, iron oxide, and magnesium oxide burned together in a kiln and finely pulverized and used as an ingredient of mortar and concrete. CONCRETE: ...a hard strong building material made by mixing a cementing material (as portland cement) and a mineral aggregate (as sand and gravel) with sufficient water to cause the cement to set and bind the entire mass.
