What is a patent lawyer, and how is that different from a patent agent?

"Patent lawyer" and "patent attorney" are used interchangeably; both are licensed attorneys qualified to draft, file and prosecute patents and provide legal advice more broadly, including litigation. A patent agent, by contrast, can handle the same technical patent work but isn't a licensed attorney and can't represent clients in court. This attorney/agent split is US terminology; in Europe, "patent attorney" is itself the qualified profession, distinct from a general lawyer.