Complete Memory Dump: A complete memory dump records all the contents of system memory when your computer stops unexpectedly. A complete memory dump may contain data from processes that were running when the memory dump was collected.
* must have a paging file on the boot volume
*  previous file is over written if a second problem occurs
Kernal Memory Dump:A kernel memory dump records only the kernel memory. This speeds up the process of recording information in a log when your computer stops unexpectedly. You must have a pagefile large enough to accommodate your kernel memory. For 32-bit systems, kernel memory is usually between150MB and 2GB. Additionally, on Windows 2003 and Windows XP, the page file must be on the boot volume. Otherwise, a memory dump cannot be created.
It includes only memory that is allocated to the kernel and hardware abstraction layer (HAL) in Windows 2000 and later, and memory allocated to Kernel-mode drivers and other Kernel-mode programs, not include unallocated memory or any memory that is allocated to user-mode programs
* previous file is over written if setting is checked
Small Memory Dump
A small memory dump records the smallest set of useful information that may help identify why your computer stopped unexpectedly.A history of these files is stored in a folder
    The Stop message and its parameters and other data
    A list of loaded drivers
    The processor context (PRCB) for the processor that stopped
    The process information and kernel context (EPROCESS) for the process that stopped
    The process information and kernel context (ETHREAD) for the thread that stopped
    The Kernel-mode call stack for the thread that stopped
* If a second problem occurs and a second small memory dump file is created, the previous file is preserved. Each additional file is given a distinct name. The date is encoded in the file name. For example, Mini022900-01.dmp
To configure startup and recovery options (including the dump type), follow these steps:
    Click Start, and then click Control Panel.
    Click Performance and Maintenance, and then click System.
    On the Advanced tab, click Settings under Startup and Recovery.
Tools for the dump types :
I386kd.exe. - complete & kernla dumps with the windows 2000 support
Dumpchk.exe  - Small memory Dumps