Example of Static Resource Vs Dynamic Resource

In XAML:

<Window x:Class="WpfApplication.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApplication"
        mc:Ignorable="d"
        Title="MainWindow" Height="500" Width="500" Loaded="Window_Loaded">
    <Window.Resources>
        <SolidColorBrush Color="Red" x:Key="buttonRedBackground"/>
    </Window.Resources>
    <Grid>
        <WrapPanel Name="wrapPanel" Margin="120,0,0,0">
            <Button Name="Button1" Content="Button - Static Resource" Width="250" Height="50" Margin="10"  Background="{StaticResource buttonRedBackground}"/>
            <Button Name="Button2" Content="Button- Dynamic Resource" Width="250" Height="50" Margin="10" Background="{DynamicResource buttonRedBackground}" />
        </WrapPanel>
    </Grid>
</Window> 

In these I created a resource named "buttonRedBackground" which has "Red" background and assign these resource to both buttons. Then, in code behind I change the background of "buttonRedBackground" resource and change its background to green. 
Then you will see in static resource button the colour is still red and in dynamic resource button colour is change to green.

In Code Behind:

private void Window_Loaded(object sender, RoutedEventArgs e)
	{
		wrapPanel.Resources["buttonRedBackground"] = Brushes.Green;
	}

OUTPUT:

Hope this sample will help you. Thanks