If you are in a real project knowing the difference between mediation and orchestration is important.
In my previous blog entry I gave a short introduction into the different types of processes.
If found some interesting articles that provide more detailed information about the subject.
A good article written by Satadru Roy about mediation and orchestration can be found at
SOA infrastructure: Mediation and orchestration
Another one written by Ronan Bradley is:
ESB: saving SOA from a dead end