1.5 GB VRM vs 3 GB VRM - how much of a difference will it make?

When gaming, yes, there's better performance due to a large amount of memory on 1.4Gb card than a 1gb card this happens on resolutions higher than 1080p, when you set these settings AA and AF to 4x and up, and better textures quality, the more GDDR is used to save and show up in screen, when there's lack of memory it performs poorly because it uses the system DDR memory increasing latency and consequently less FPS. hope this is clearly enough.