Agent
An agent is a type of AI that can perform more complex tasks on its own - without you giving it each step individually. Just tell it the goal, and it will plan its own way to it.
While a conventional model like ChatGPT answers one specific prompt, an agent can break the task into smaller parts, think about the process, and make decisions in multiple steps. It is suitable for more complex tasks, planning and automation.
Tools that already work with agents include OpenAI Deep Research or advanced versions of ChatGPT.
Multi-agent
Multi-agent is a system in which multiple AI agents work together at the same time - each has its own task, but together they solve one larger problem. They work autonomously but collaborate together, much like a team of humans.
Practically? A multi-agent system could, for example, plan a marketing campaign by itself: one agent researches the market, another prepares the texts, a third analyses the results and optimises the strategy in real time.
Currently, there are only a minimum of multi-agent systems in production. Most of them have not yet reached a level where they can undergo extensive user testing. These are very robust solutions.