There's going to be one big difference between the downloaded Facebook Home and the one that arrives pre-loaded on the HTC First -- Notifications. The HTC First eats them all up and spews them out in the Facebook Home style, but the downloadable launcher for other phones can't intercept the standard Android news updates.
That's a good thing according to HTC, which claims this provides a "seamless" way for newcomers to Facebook Home to stay 100 per cent absorbed within its new walled garden when using the HTC First. But for Android enthusiasts, it's going to mean notifications for the usual Android features won't be incorporated into Facebook Home when using the download version, so you'll be dumped back to your phone's standard launcher when popping off to read an email. [Pocket-Lint]