Best bet is to visit each web site and compare the features that are important to you.
Way to many to list.
Carte Du Ciel may be all you need .
For my self I required the better integration of Observatory CCd imaging and Scope Controll of The Sky but found CDC to be the best of the freeware programs .
http://www.bisque.com/Products/TheSky6/
http://www.starrynight.com/pro_plus.html
http://www.stargazing.net/astropc/index.html