This widget's full name is iwidgets::datefield.
The full name for this widget appears to be ::datefield::datefield .
Its documentation can be found at http://tcllib.sourceforge.net/doc/datefield.html
One difference between the two is that at least in one environment, the default background of the iwidgets datefield is grey, while the default background of the tklib version is bisque ...
KPV huh? It's just an entry widget with special bindings. What color it is is whatever the tk default unless the user specifies otherwise.
beernutmark 2008-09-20 : A more functional difference is the ability to set the intelligence of the iwidgets::datefield to low. This allows for dates of 0000-00-00 or any other nonsensical dates. The ability to enter dates of 0000-00-00 can be important for storing in a mysql database to indicate that the date has not yet been determined.