What do they mean by aligned teeth?

[Braces and Invasalign]

Is it when all the teeth from bottom jaw and top jaw are in contact when jaws are closed? Or does it have anything to do with the teeth all aligned together with no gaps between teeth?

I'm 21, and when I close my jaws, I notice not all teeth are in contact with the corresponding teeth on lower jaw, but when I move my top jaw forward and top teeth are no longer touching the ones on the bottom, I notice there is no longer a gap between the molars from top jaw and bottom jaw.