Hi Kiran Mandapati,
Selecting through code leads to "SelectionUnfocused" visual state and you see the RadTreeViewItem with gray background. When you select with mouse , you also focus the RadTreeViewItem and it goes to "SelectionFocused" visual state (orange-like background). You either have to focus the item in the code or change the default style of the RadTreeViewItem and play with the mentioned colors (they are Backgrounds in the "SelectionFocused" and "SelectionUnfocused" Borders).
the Telerik team
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