The two packages do more-or-less the same thing: they waste project time by becoming used as a tool for beating-up the project team when key dates are not met.

The worst thing that both of them have is a "print" button.

There is no comparison!

Primavera is a very good project planning tool, it is extremely powerful and its correct use can save a fortune over the life of a project - resource levelling etc etc

MS Project is - well it is MS project. OK if you want to let your boss or the client know the start and end date of a project with a few activities and links etc.

Just compare the difference in price! Horses for courses, if you want to schedule the overhaul of a pump then MS is fine, if you want to build a refinery then use Primavera or similar.