drumme girl,
Most camcorders do "overscan" and actually capture a bit more than you see in the viewfinder or on the LCD. Because of this, some info on the edges (left, right, top, bottom) will not be displayed when played back. This also depends to some degree on what device you playing back on and what format too.
The TV safe zone is exactly that, what you would expect to be visible when burnt to disc and played on a home entertainment system. Good guage for titles, PIP tracks and so on. In general I've seen that it is a pretty good estimate. I once put items in the 4 corners so I could map out the safe zone manually and found that the PD7 TV safe zone was a little conservative. However, I also found a difference in safe zone when the same DVD was played on 2 different LCD TV's and 2 different Tube (CRT) TV's. A safe zone exists with both 4:3 or 16:9.
Jeff