In TN coaches consider what jimmypop described as

limited (i.e., not full) contact, even at full speed. I'm sure different places use different definitions and terms, but good luck getting uniformity.

Personally, I think the key injurious actions occur around the legs and knees that occurs with tackling to the ground or low block/leverage situations.

Of course there's the usual caveats about using one's head or going to another player's head; however those are actions that coaches are trying to eliminate anyway (not that they still don't happen).

My opinion, however, is that these policies serve to reduce the # of potential injurious plays but not change the nature of play. That is, injuries caused by contact will still happen.