Overburden refers to the material above the resource to be mined. Overburden has little or no interest to the mine operation in terms of economic value although it is useful in haul road construction, mine reclamation as fill dirt, and other various mine activities. Overburden removal is one of the expenses accrued before actual mining can begin.
Interburden is similar to overburden in that it has little or no economic value, but it is located between regions/layers of interest. Interburden does not necessarily increase mining costs significantly, but it usually increases processing costs since this material must be removed from the valuable material within a mill (or processing plant).
Figure: As seen above, there is distinct differences between the geological layering of overburden and interburden.