Difference between X(Synchrnonous)FrameLoader and XComponentLoader?

[Tor Lillqvist]

XFrameLoader / XSynchronousFrameLoader are interfaces for 'loading of
the specified resource [which apparently can mean "document"] into the
specified Frame' (asynchrnously or synchronously).

XComponentLoader is an interface to 'load components [and based on how
it is used in sample code, "component" here can mean "document"] by an
URL into a frame environment'. What's the difference?

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