JavaFX provides a feature Drag-to-Install simply by dragging them out of your browser - you can then relaunch the applications directly from your desktop. How different is it different from JNLP? Or how easy or advantageous it is over JNLP in terms of distributing content over the web?
I think you're mixing things.
JNLP is just a way of deploying your application, while JavaFX is a presentation layer.
In fact you can deploy your JavaFX code in a JNLP package.
You should compare JavaFX with Swing ;)
With JNLP you can distribute Swing or AWT or SWT or JavaFX java applications. Having the posibility to execute then in a sandbox.
Both the applet and webstart methods of deploying JavaFX applications use JNLP files.
This is a change from the past when JNLP was only used by WebStart (which is what you are referring to).
There isn't much difference, it depends on the user experience you want the user to have. I would say for most significant apps, you are better off with the more traditional webstart method of launching apps (download a JNLP file from a link and have javaws launch it).
There are subtle differences in the security privileges between a applet and webstart, further more there are also some API differences inside JavaFX between what works in an applet vs what works in a webstart launched app. These are being slowly eliminated.