Difference betwen and in CRM 2011 Ribbon

Hi All,

Can anyone give the difference between <EnableRules> and <DisplayRules> in CRM 2011 ribbon. I find both of them as similar in the below URL.

http://msdn.microsoft.com/en-us/library/gg334682.aspx

http://msdn.microsoft.com/en-us/library/gg328560.aspx

Thanks in advance.

Thanks

Vikram