Complete memory dump
A complete memory dump records all the contents of physical memory (RAM) at the time of the crash. A complete memory dump may contain data from processes that were running when the memory dump was collected. If a second crash occurs and another complete memory dump (or kernel memory dump) file is created, the previous contents of the C:\Windows\MEMORY.DMP file are overwritten.
By default, the complete memory dump option is not available in Startup and Recovery
on computers that have 2 gigabytes (GB) or more of RAM installed. You can still set Windows to create a Complete memory dump using the REG file in step 4 of Option Two below though. The complete memory dump will require that there is a page file set to at least the size of physical memory installed plus 1MB (for the header). Kernel memory dump
A kernel dump contains only the kernel-mode read / write pages present in physical memory at the time of the crash. Since this is a kernel-mode only dump, there are no pages belonging to user-mode processes. However, it is unlikely that the user-mode process pages would be required since a system crash (bugcheck) is usually caused by kernel-mode code. The list of running processes, state of the current thread and list of loaded drivers
are stored in nonpaged memory that saves in a kernel memory dump. The size of a kernel memory dump will vary based on the amount of kernel-mode memory allocated by Windows and the drivers that are present on the system.
If a second crash occurs and another kernel memory dump (or complete memory dump) file is created, the previous contents of the C:\Windows\MEMORY.DMP file are overwritten. Small memory dump
A small memory dump (Minidump) is a C:\Windows\Minidump dump file that contains the stop code, parameters, list of loaded device drivers, information about the current process and thread, and the kernel stack for the thread that caused the crash.