difference between SPListItem.SystemUpdate and SPListItem.Update Method

http://www.codegain.com/articles/sharepoint/developmentprogramming/what-is-the-difference-between-splistitem-systemupdate-and-splistitem-update-method.aspx 

SPListItem.SystemUpdate:

Updates the database(Sharepoint list) with changes that are made to the list item, without effecting changes in the Modified Time or Modified By fields.

SPListItem.SystemUpdate Overloaded Method:

SPListItem.SystemUpdate():
Updates the database with changes made to the list item, without effecting changes in the Modified or Modified By fields.

SPListItem.SystemUpdate(Boolean):
Updates the database with changes that are made to the list item, without effecting changes in the Modified Time or Modified By fields, or optionally, the item version.

Example:

{codecitation class=" xml; gutter: true;" width="650px"}

//Take the reference of that item

SPListItem listItem = listItemCOll[icount];

listItem["FIRST_NAME"] = “Amit”;

listItem["LAST_NAME"] = “Kumar”;

listItem["EMAIL_ADDR"] = “mcapassion[at]gmail.com”;

//Update the Item

listItem.SystemUpdate(false);

{/codecitation}

The argument false informs the SP object Model not increment versions.



SPListItem.Update:

SPListItem.Update():
Updates the database(Sharepoint list) with changes that are made to the list item/new version of item, and changes in the Modified Time or Modified By fields.


Example:

{codecitation class=" xml; gutter: true;" width="650px"}

//Take the reference of that item

SPListItem listItem = listItemCOll[icount];

listItem["FIRST_NAME"] = “Amit”;

listItem["LAST_NAME"] = “Kumar”;

listItem["EMAIL_ADDR"] = “mcapassion[at]gmail.com”;

//Update the Item

listItem.Update();

{/codecitation}