AI agent or automation: what's the difference and which do you need?

An automation is a fixed sequence of steps that runs when a trigger fires. A person decides every step in advance, so the same input always takes the same path. A web form entry that creates a CRM contact, sends a welcome email and posts in Slack is an automation.

An AI agent is software in which a language model decides what to do next. It reads the situation, picks a tool, looks at the result and repeats until it meets the goal or hands over to a person. Nobody knows the number of steps in advance.

An automation with an AI step sits between the two. The path is fixed, but one step calls a model to classify an email, pull fields from an invoice or draft a reply. Zapier analysed 10,000 of these AI-powered workflows on its own platform, and the results are below.

Anthropic, which makes the Claude models, draws the same line. It describes workflows as systems "orchestrated through predefined code paths" and agents as systems in which the model directs its own process and tool use (Building effective agents, December 2024).

Most of these are automations with one or two AI steps. Invoice and document work is covered in AI document processing, and support answers in AI customer support.

An automation costs less to build and far less to run. On Softomate's 2026 UK price list, a simple n8n or Make automation starts at £1,500 plus £99 a month, and a controlled AI agent at £6,500 plus £399. A practitioner on r/AI_Agents who charges $3,000 for automations says 90% of the agent projects he is hired for don't need agents. A commenter added that a $3,000 automation saving 20 hours of manual work beats a $50,000 agent that solves nothing.

Worked example with 1,000 inbound emails a month

Here is what sorting 1,000 emails a month costs with an automation and one AI step.

• On n8n Cloud, each email is one workflow execution, so the €20 a month Starter plan with 2,500 executions (annual billing) covers it.
• On Zapier, if each email uses three tasks, that is 3,000 tasks a month. The 2,000-task Pro tier is too small, so it needs the $89 a month tier with 5,000 tasks (annual billing).
• A classification call with 1,500 input tokens and 50 output tokens costs $0.000175 on Claude Haiku 5.5 (1,500 tokens at $0.10 per million plus 50 at $0.50 per million). For 1,000 emails that is about 18 cents a month.
• The same call on Claude Sonnet 5.5 costs $0.0035, or $3.50 a month.

Handing each email to an agent costs more. Assume 20,000 input tokens and 2,000 output tokens per email as the agent reads the thread, checks systems and drafts a reply. On Claude Sonnet 5.5 that is $0.04 plus $0.02, or $0.06 an email, which comes to $60 a month for 1,000 emails before hosting.

The agent's model bill is about 17 times the AI step's on the same model ($60 against $3.50), and it needs more testing. Those token counts are assumptions, so measure your own before you budget. The agent earns that extra cost only when the work can't be written as fixed steps. For full build and running figures see how much an AI agent costs.

Yarigai builds AI agents, inbox triage, document reading and filing, invoice chasers and receipts into Xero or QuickBooks, inside the client's own accounts and tools. The blueprint, which takes about a week and is credited to the build, puts the agent or automation question on paper before any build starts. It sets out a written plan, a clickable prototype, the monthly running cost, a fixed price and the payback maths.

A person approves anything that sends money, emails a customer or deletes data. The client owns the code, the data and the accounts from day one, and pays AI and hosting bills at cost. A single workflow can go live in about two weeks, and larger builds take 2 to 6 weeks with a demo of working software every week. Yarigai quotes a fixed price after the one-week blueprint, and its guarantee reads "If the build isn't profitable for you, we won't build it." More on AI agents and AI operations.