robustness
The so-called "robustness" refers to the control system's ability to maintain certain other performance characteristics under certain (structure, size) parameter perturbations.
stability
The so-called "stability" refers to the ability of the control system to return to its original equilibrium state after the disturbance that caused it to deviate from the equilibrium state disappears.
comprehensive analysis
Robustness is the ability of a system to maintain stability when its internal
parameters change; stability is the ability to maintain stability when the system is subject to external disturbances .