Minimal consciousness is not uncommon after a severe brain injury, affecting at least 25,000 people in the United States. But unlike a coma, which usually lasts only a few weeks after an accident, a minimally conscious state can be prolonged for months or years. Patients are for the most part unaware of their surroundings and unable to communicate, but they may occasionally utter words, reach for objects, or respond to questions. (This condition is distinct from the vegetative state, which can also last for months or years but is not characterized by such intermittent awareness.)

Schiavo was, of course, in a persistent vegetative state and not a state of minimal consciousness, so there was no hope for the kind of recovery the very fortunate Mr. Wallis had.

Ms. Schiavo suffered more profound brain damage than Mr. Wallis and did not show signs of responsive awareness, according to neurologists who examined her. [New York Times]

The hopelessness of Schiavo's condition was confirmed by her autopsy:

Schiavo's brain damage "was irreversible . . . no amount of treatment or rehabilitation would have reversed" it, said Jon R. Thogmartin, the pathologist in Florida's sixth judicial district who performed the autopsy and announced his findings at a news conference in Largo, Fla. [Washington Post]

Of course, these facts won't stop the right from pressing ahead -- ideology always trumping reality for them:

Terry Wallis’ remarkable recovery after 19 years, however, stands in stark opposition to the case of Terri Schindler-Schiavo, who received no therapy from her philandering husband after her 1990 collapse. She was instead dehydrated to death by court order in March 2005. Although some doctors claim that Terri Schiavo could not have made Terry Wallis’ recovery since she was in a persistent vegetative state (PVS), witnesses such as former nurse Carla Iyer maintained that with therapy, Schiavo, who said words like “mommy, help me”, could have indeed recovered over time. [LifeSiteNews]

Autospy evidence be damned! They want her to have been able to speak and see (the autopsy determined that she was blind), so she must have spoken and seen. Ideology demands it, and so it must be.

Update: Jake Young at Pure Pedantry has a lot more on the difference between a state of minimal consciousness and a persistent vegetative state:

To emphasize the point, there is a huge area of difference between someone who has essentially only the housekeeping functions in the brain and someone who -- for reasons metabolic or traumatic -- comes in and out of consciousness intermittently. It is very unfortunate that Terry Wallis was misdiagnosed in this case, because the prognosis for individuals with minimally conscious state -- while not fabulous -- is much better than for a persistent vegetative state. I just thought I would get the distinction out of the way early lest people go into a flurry of speculation about how all people in comas now have the possibility of recovery. Terry Wallis had a possibility of recovery because he had a condition that allowed for recovery. Terry Schiavo did not.

There's a lot more as well.