A Microburst is an intense small scale downdraft which is produced from a rain shower or thunderstorm.
A downburst is a strong level wind that comes from a point source above and it blows in straight lines in every direction from the point of contact at ground level.
A downburst is sometimes confused with a tornado although they're entirely different but both can cause a lot of damage.
During a Tornado High Velocity winds circle a central area while during a downburst the wind is directed downward and then again outward from the landing point of the surface.