Vray supports OCIO, so it’s recommended to download the ACES OCIO implementation and set the V-Ray Frame Buffer to use it.
V-Ray OpenColorIO Support
There he can set the Input Colorspace to ACEScg, so both of you will see the same result (hopefully…). Otherwise the renderer would directly feed the image - with gamma correction - to the monitor, which isn’t ok for many reasons.
Additionally using ACEScg in the render view means that the relative primaries of the renderer are now defined and the input colour textures (even the linear ones), which are not in ACEScg should have a conversion with the VRayOCIO texture converter. Linear data textures like normal map, bump, specular intensity etc. doesn’t need this. I didn’t use this OCIO support in V-Ray, so I have no experience how it performs in practice…