It says that the real difference between Full HD and HD Ready is that Full HD operates at a full 1920x1080 resolution and accepts HD signals. HD Ready means that it accepts HD signals but can have a resolution of less than 1920x1080 (and probably will have a lower resolution). You could use either Full HD or HD Ready in a home theater system, but no one likes lowered resolution, so Full HD is definitly the better choice.
IMHO, the term "HD ready" is a marketing term designed to get you to buy an obsolete product. That was certainly the case when I bought one of the last CRT TVs available a few years ago. As it turned out that TV didn't do anything different than any other analog TV then available. I suggest a careful scrutiny of the specs rather than undefinable terms like "HD ready" as a buying guide. BTW, if you haven't investigated 3D TV yet you should. It appears that 1080p will be the old "full HD" in the near future. If you buy something less now it is almost certain to be in the trash shortly.