Whats the difference between Keyboard.Focus(item) and item.Focus()?

Question

In WPF, there are two ways to set the focus to an element.
You can either call the .Focus() method of the input element, or call Keyboard.Focus() with the input element as parameter.

// first way:
item.Focus();
// alternate way:
Keyboard.Focus(item);

What is the difference between these two? Are there special reasons to use one of them instead of the other in some cases?
So far I noticed no difference - what ever method I used, the item always got logical focus as well as keyboard focus.

Answer 1

One of the first things that item.Focus() does is call Keyboard.Focus( this ). If that fails, then it makes calls to FocusManager, as decasteljau has answered.

The following are copied from disassambler view in Reflector.

This is from UIElement (UIElement3D is the same):

public bool Focus()
{
    if (Keyboard.Focus(this) == this)
    {
        return true;
    }
    if (this.Focusable && this.IsEnabled)
    {
        DependencyObject focusScope = FocusManager.GetFocusScope(this);
        if (FocusManager.GetFocusedElement(focusScope) == null)
        {
            FocusManager.SetFocusedElement(focusScope, this);
        }
    }
    return false;
}

This is from ContentElement:

public bool Focus()
{
    return (Keyboard.Focus(this) == this);
}