Recent advances in large language models (LLMs) such as GPT-4o offer the potential for enhancing AI-driven robotic interactions, but their effectiveness in mobile tour guidance remains unexplored. This study investigates the differences between human-operated and AI-driven guidance at an aquarium using Teleco, a teleoperated mobile robot, in a real-world field experiment. A total of 277 guidance sessions were collected under two modes: human-operated, where the operator controlled all dialogue, actions, and movement, and AI-driven, where GPT-4o generated responses while the operator only controlled the robot’s actions and movement. Our results indicate that human-operated guidance places greater emphasis on visitor movement, spatial positioning during observation guidance, and empathetic expressions, whereas AI-driven guidance promotes conversational engagement by frequently prompting visitors to ask questions. In addition, we found that user behaviors, including users’ gaze patterns and vocabulary richness, also serve as valuable indicators reflecting their overall experience during guidance interactions. Furthermore, empathetic expression is recognized as the key differentiating factor between the two guidance modes, significantly influencing users’ overall experience.