Virtual memory may be implemented in different ways in different operating systems, such as Windows and Linux, but the core concept is the same; you are simulating more memory than you have by temporarily putting it on disk. The idea is the same between the two operating systems, and the way of implementing may be very different.
From the user's point of view they are the same.
Virtual Memory Manager
By the VMM Virtual Memory manager
The difference between virtual and physical memory is that virtual memory refers to memory space while physical memory are chips like RAM. The memory space for virtual memory is made by operating system when there is insufficient physical memory.
pagefile is the virtual memory
If a person is getting a message that says they are running low on virtual memory from their pc, it usually means that Windows isn't managing the memory correctly. If the virtual memory minimum is too low, then a person can go into the system and edit the amount of virtual memory manually which should fix the problem.
Virtual memory is determined by 2 factors. First, the amount of free hard drive space available on your hard drive. Secondly, it is determined by your virtual memory settings under Windows properties. Assuming you have not changed your Windows default settings, then every ounce of free harddrive space IS virtual memory.
All versions of Windows from Windows 95 and later use virtual memory. Virtual memory is a complex and sophisticated system, it is NOT the pagefile. This system is always in use and cannot be disabled.
If you are using a modern version of Windows (Windows 95 or latter) you will be using virtual memory. Virtual memory is NOT the pagefile and it is not an extension to physical RAM but a system that is completely integrated into the system. Applications access virtual memory exclusively, no exceptions, ever. You can not disable virtual memory. You can disable the pagefile (not recommended) but this will not disable virtual memory. The system provides a virtual environment to processes that is completely independent of how much RAM is in the system. This is an advanced system that provides many important advantages to applications and users.
YOU CAN'T! Virtual memory is a system that is always in use and cannot be disabled. It is not the pagefile and it is not an extension of physical memory. Applications use virtual memory exclusively and never access RAM directly.
C:\pagefile.dat
It's purpose is to give the Windows operating system extra space to enable it to work properly. If a computer has insufficient RAM, Windows can use free space on the hard-drive as virtual memory.
pagefile.sys