The differences between these two are listed below:
o A beta test when the product is about
to release to the end user whereas 
pilot testing take place in the earlier phase
of the development cycle.
o In beta testing application is given 
to a few users to make sure that application
meet the user requirement and does
not contain any showstopper whereas
in case of pilot testing team member 
give their feedback to improve the quality
of the application.