WPF DataTemplate DataType

//xaml
<Window x:Class="WpfApp77.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:WpfApp77"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Window.Resources>
        <DataTemplate  DataType="{x:Type local:Person}">
            <Border BorderBrush="Green" BorderThickness="5">
                <StackPanel Margin="4">
                    <TextBlock Foreground="Red" FontSize="20" Text="{Binding Name}" TextAlignment="Center"/>
                    <TextBlock FontSize="16" Text="{Binding Age}" TextAlignment="Right"/>
                </StackPanel>
            </Border>
        </DataTemplate>
        <DataTemplate DataType="{x:Type local:Employee}">
            <Border BorderBrush="Black" BorderThickness="1">
                <StackPanel Margin="4" Orientation="Horizontal">
                    <TextBlock Foreground="Blue" FontSize="20" Text="{Binding Name}"
                               TextAlignment="Center"/>
                    <TextBlock Foreground="Red" FontSize="16" Text="{Binding Department}"
                               Margin="20,0,0,0" VerticalAlignment="Center"/>
                </StackPanel>
            </Border>
        </DataTemplate>
    </Window.Resources>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <!--<Button Content="{Binding}"  ContentTemplate="{StaticResource ResourceKey=personTemplate}" />-->
        <ListBox Grid.Row="1" x:Name="_lbx" 
                 HorizontalContentAlignment="Stretch" 
                 ItemsSource="{Binding}"/>
    </Grid>
</Window>


//cs
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApp77
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            DataContext = new Person { Age = 10, Name = "Fred" };
            InitLbx();
        }

        private void InitLbx()
        {
            ObservableCollection<Person> personsCollection = new ObservableCollection<Person>
            {
                new Person { Name="Bart",Age=10},
                new Employee { Name="Homer",Age=45,Department="CS"},
                new Person {Name="Marge",Age=35},
                new Employee{Name="Lisa",Age=12,Department="Math"},
                new Person{Name="Maggie",Age=1}
            };
            DataContext=personsCollection;
        }
    }

    public class Employee : Person
    {
        public string Department { get; set; }
    }

    public class Person
    {
        public string Name { get; set; }
        public int Age { get; set; } 
 
    }
}