The big difference is that the Worldbox is USB 2.0 Only where the Starbox is either 1.0 or 2.0.
The included software with the Woldbox will do 4:2:2 & HD where with the Starbox you might have to find a codec.
The Woldbox is gaining support with the 3rd party apps so it's really a toss-up.
I went for the Worldbox from a DMSI dealer and I'm happy with it.