A patent agent is qualified to represent clients before the national patent office with a view to obtaining a patent. All patent agents have to have passed a rigorous examination in order to register to practice their profession. They provide client confidentiality with regards to the filing of patents. A patent agent will typically have a science or engineering degree, and sometimes a PhD. A registered patent agent should be listed on the website of their national patent office.
A patent lawyer has a law degree and is usually qualified as a patent agent. A patent lawyer can do additional tasks compared to a patent agent, such as drafting contracts or representing a client in a patent dispute. A patent lawyer will often have a technical degree as well.
A patent attorney may refer to either a patent agent or a patent lawyer, depending on where they are. In Europe, a patent attorney is the same as a patent agent. In the US, a patent attorney is the same as a patent lawyer.