Aliasing:

    A stair step lines or jagged edges.low frequency lines.

Anti-aliasing:

   A smooth curves or lines. no jagged lines here.by applying particular technique to smooth out the edges for better overall picture. This might workout by slightly blurring it.

In the below image the letters are having jagged lines.
Example for Anti-aliasing:

Where we use:
1.Photos 

2.Video games




Notes: