What is the difference between a patent assignment and a patent license?

The key differences between a patent assignment and a patent license are:

• Assignment: Transfers all or part of the ownership interest in a patent, including the entire bundle of rights associated with ownership.
• License: Transfers a bundle of rights that is less than the entire ownership interest. It may be limited in time, geographical area, or field of use.

A license is essentially a contractual agreement that the patent owner will not sue the licensee for patent infringement under certain conditions. Even an exclusive license is not considered an assignment of patent rights.