HD Ready means ready for High Definition. It is an industry standard for a new generation of display devices like plasma TVs, LCD TVs and projectors. HD Ready projectors will display pictures with a much higher resolution than SD or Standard Definition projectors.
The EICTA "HD Ready" minimum requirements for display devices are the same no matter what type of display device you own (e.g. plasma, LCD, DLP, DLA, LCoS, CRT), and no matter which display method you use (e.g. flat panel, rear projection, front projection, direct view).
Minimum specifications for a display device to be called HD Ready
The minimum native resolution of the display (e.g. LCD) or display engine is 720 physical lines in wide aspect ratio, for example the EPSON EMP-TW520 and EMP-TW600.
The display device accepts HD input via:
Analogue YPbPr input, and
Digital DVI or HDMI input.
HD-capable inputs accept the following HD video formats:
1280x720 @ 50 and 60Hz progressive ("720p"), and
1920x1080 @ 50 and 60Hz interlaced ("1080i")
The DVI or HDMI input supports High-bandwidth Digital Content Protection (HDCP).
Clarity of displayed resolutions
HD TV means High Definition Television. This relates to receivers and TVs.
EICTA have also created an official specification for HD Television Receivers with or without a display for video reproduction.
The requirements for a HD Television Receiver without a display for video reproduction (which can be used with a video projector) are:
Display, display engine
Same as for HD Ready.
You can use a variety of video interfaces. The Output interfaces required are Analogue YPbPr, DVI or HDMI.
If the HD Television Receiver is intended to be used with HD sources (television broadcasts) some of which require content protection to permit HD quality output, then the HD Television Receiver should implement an HDMI or DVI interface with support for HDCP.
There is no minimum native resolution required, the aspect ratio can be other than wide (4:3 is allowed, for example) and also no specific connection is required.
Full HD, HD Ready 1080p, HD TV 1080p
The minimum native resolution of the display (e.g. LCD) or display engine is 1080 physical lines in wide aspect ratio. The device should display the 1920 x 1080 @ 50 and 60Hz in native resolution.