The Virtual Server is a partitioning of the software capabilities of a physical server (VMware Esxi, HyperVM, SolusVM, etc.) so that each system has its own resources. There are 2 types of Virtual Server, VDS and VPS.
Virtual Dedicated Server (VDS)
Virtual Private Server (VPS)
VDS is simply a virtual server dedicated to you. It acts like a real server.
VPS are virtual servers, which are briefly separated by common resources. It uses the core structure in the main machine. It does not pretend to be a real server.
I hope this information is of your interest.
If there is any detail you want to ask, you can post it as a comment.