Discrimination between $Z'$ -boson and anomalous gauge couplings effects in $e^+e^- \to W^+W^-$ at ILC

We discuss the foreseeable sensitivity to $Z'$s of $W^±$-pair production cross sections at the $e^+e^-$ international linear collider (ILC), especially as regards the potential of distinguishing observable effects of the $Z'$ from the analogous ones due to competitor models with anomalous trilinear gauge couplings (AGC) that can lead to the same or similar new physics experimental signatures at the ILC. the model independent analysis of the $Z'$ effects in the process $e^+e^- \to W^+W^-$ allows to differentiate the full class of vector $Z'$ models (except sequential sm (ssm)-like models) from those with anomalous trilinear gauge couplings. results of model dependent analysis of a specific $Z'$ are expressed in terms of discovery and identification reaches on the $Z - Z'$ mixing angle and the $Z'$ mass.