Artificial intelligence is a broad term that covers concepts such as RPA. In Artificial Intelligence, a machine tries to mimic and apply human thinking into a process or workflow, whereas, RPA is a rule-based software that has no intelligence and only automates repetitive tasks based on the set conditions.
You can infuse RPA with AI and many vendors are in the pilot stage of doing so. For instance, an application of AI in RPA could include image recognition or text analysis.