Tool life of the traditional cutting tools is comparatively lesser on machining the martensitic stainless steel AISI 416 which is one of the hardest materials. In order to increase the tool life, wear-resistant nanocoatings on the cutting tools have been explored. This study enunciates a comparison of tool life between PECVD (plasma-enhanced CVD multilayer nanocoated) and PVDMNC (PVD multilayer nanocoated) cutting tools on turning a martensitic stainless steel AISI 416 by experimental and theoretical investigations in addition to exploration of the machinability studies of cutting tool flank wear, tool hardness and surface roughness of work material. An orthogonal design, signal-to-noise ratio and Analysis of Variance (ANOVA) methods were employed to confirm the parameters like cutting speed, tool hardness and feed rate that are involved in the study to estimate the cutting toollife. The investigations confirmed that cutting speed was the most dominant factor in determining tool life while comparing with other parameters. It was observed from the ANOVA results that the cutting speed, tool hardness, and feed rate have contributed 41.44%, 33.79%, and 24.35% respectively in determining the tool life of PECVD cutting tools whereas the contributions of the same parameters were found to be 40.01%, 32.90%, and 26.63% respectively for PVDMNC cutting tool. It is evident from the results that the cutting performance of the PECVD cutting tool is superior in terms of cutting speed and hardness which were enhanced by 1.43% and 0.89% respectively in addition to lesser wear rate when compared to the performance of PVDMNC cutting tools. Nomenclature ANOVAAnalysis of variance F Feed rate (mm/min) CVD Chemical Vapor Deposition Process V Cutting speed (m/min) PVD Physical Vapor Deposition Process S/N ratio Signal-to-noise ratio PE Plasma Enhanced MS Means of squares DOC Depth of cut DF Degree of freedom F va The value of variance T Tool life HV Hardness value by Vickers