Hi,
From what I can see - it's just the addition of the DVI-HDCP adaptor on the RD50H model.
The model being sold in the UK (as of 2 weeks time) is the Optoma ThemeScene RD50 - which comes with DVI-HDCP adaptor - so will essentially be the RD50H with regional changes.
Here's the "differences" for the USA models, as published on the
http://www.optomatv.com site:
RD50 Specifications
User-friendly Features
Multiple connectors (DVI, BNC RGB, Composite, S-Video, RF, VGA, YPbPr)
DVI connector ensures connectivity with future digital devices
Individual picture adjustment memory for each input source
Nine display formats for flexible re-sizing and display
2-tuner Picture-In-Picture (PIP) and Picture-On-Picture (POP)
Favorite channel memory
Two built-in 15-watt stereo speakers
Intuitive Onscreen Display design for easy operation
Image Processing Technology
HDTV-ready for 480p, 1080i and 720p formatted media
Precision Pixel Matching (PPM) technology for 1:1 scan conversion
Unique color gamma fine tuning can be manually adjusted
DVDO 504 Progressive Processing for artifact-free scaling
3D Digital Comb Filter for sharp and noiseless video signals
RD50H Specifications
User-friendly Features
Multiple connectors (DVI, BNC RGB, Composite, S-Video, RF, VGA, YPbPr)
DVI-HDCP connector ensures connectivity with future digital devices
Individual picture adjustment memory for each input source
Nine display formats for flexible re-sizing and display
2-tuner Picture-In-Picture (PIP) and Picture-On-Picture (POP)
Favorite channel memory
Two built-in 15-watt stereo speakers
Intuitive Onscreen Display design for easy operation
Image Processing Technology
HDTV-ready for 480p, 1080i and 720p formatted media
Precision Pixel Matching (PPM) technology for 1:1 scan conversion
Unique color gamma fine tuning can be manually adjusted
DVDO 504 Progressive Processing for artifact-free scaling
3D Digital Comb Filter for sharp and noiseless video signals
Hope this helps.