Read original post at Jerry Nixon's Blog
Using a GridView in XAML is the primary way to show lists of data. The GridView inherits ItemsControl and behaves like the ListView which behaves like a classic ListBox. The GridView scrolls horizontally, handles selection, rearrangement, and (as we see in this article) also allows for variable sited items.
The GridView’s ItemsPanel is a WrapGrid by default. Unlike a VariableSizedWrapGrid, the WrapGrid creates a strictly uniform grid of items. It’s beautiful, actually. The VariableSizedWrapGrid, on the other hand, lets developers create custom and create UI.