Carlton,
I am pretty sure this post (3 in total) from Jeremy Waldrop's blog (Jeremy usually visits this community too) will help explain UCS Director: http://jeremywaldrop.wordpress.com/2014/04/01/cisco-ucs-director-part-1/
Besides what you can see in the above link... UCS Manager is usually used for a single domain while UCS Central is used to integrate more than domain into a unique central point...
HTH,
-Kenny