I like this distinction from automation by Bartosz Pucek:

At its core, an Agent is software that can:

    Take in a task description

    Break it down into steps

    Execute those steps using available tools

    Adapt its approach based on feedback

The key distinction from traditional automation: Agents handle variance and uncertainty by replanning rather than failing when their happy path breaks.

Source: https://newsletter.pucek.com/p/2025-the-state-of-ai-agents-a...