http://youtu.be/e6ns-vw4tMg
Here’s the short description for the two:
Motion Graphics equals animated graphic design. Common uses include title sequences, lower third graphics for interviews and informational art cards.
Some examples of Motion Graphics work includes:
Visual Effects combines existing footage with computer generated imagery to create realistic scenes. Common uses include sky replacements, logo removal and including environmental effects, such as snow, fire, smoke and lightning.
Some examples of this type of work include: