Value property returns the value of the group. ValueAsDisplayText returns the value converted to text. It takes into account various settings like the format, value list etc... to convert the value to the display text.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Server 2012, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2