To Display Differences Between a Local Dimension Style and the Dimension Style Library

In the Dimension Styles dialog, click the Advanced tab.
Set the Mode to Difference.
Turn on Compare with Library.
In the list box, select a local dimension style that is based on a dimension style library. These types of dimension styles are displayed with a filled book icon with a delta symbol.
For both the local style and the library style, only the dimension style settings (properties) with different values are listed.