What is the difference between microburst and windshear?
A microburst is generally an intense down draft while wind shear can occur in any direction. It might be safe to say that a microburst is windshear but not all windshear is a microburst. From your linked pages 


  A microburst is intense small-scale downdraft produced by a thunderstorm or rain shower.


and


  Windshear is any rapid change in wind direction and/or speed.