Hi
These are all different views on the same process of project managment.
Prince 2 is sponsored by the UK Office of Government Commerce, its roots are in IT project management and it has a very procedural approach to project management. Prince is a method which defines what to do and when in quite alot to detail.
PMI PMP is much wider, sponsoered but the project management institute in the USA it draws on a much wider body of knowlege. It provides a broard background to project management but leave the method to you.
ITIL is simmilar but more focused on IT issues such as requierments capture and acceptance of IT systems.
Sorry but I am not sure what you refer to as SLA aspects. They are not explicitly covered in any of the approaches.
Post a bit more detail and I will try to help you.
on-line APMP Project Management Training