Ram, or “Random Access Memory” is a type of data storage on your computer. The term “virtual RAM” is not a thing. Sorry!
VRAM, or Video RAM, is memory provided on the video card in addition to any system memory that the video card requires to run graphics applications. Essentially it’s more for graphics intensive programs like video games and graphic design software so they can have quicker access to the data they’re using. Any questions about how shared VRAM works should be directed towards the specific manufacturer of your computer because there are many different types of VRAM and each one does things differently; different manufacturers will probably use different technologies which offer benefits that others don’t provide.