Efficiency is defined as achieving maximum desired output with the given input or as achieving the given desired output with minimum input. An alternative definition of efficiency is to achieve the desired output without causing waste.
Effectiveness is the ability to achieve the desired effect, i.e. the desired output.
Robustness is the ability of a system to still function reasonably well even though it has to cope with heavy loading, adverse conditions, disturbances in execution, or reduced, erroneous or abnormale inputs.