Not really. The LLM is the data model. The part doing the language manipulation. An agent is the combination of an LLM with an interface it knows how to use to take actions with, though it may just refer to the interface or connection or tool itself.

The LLM itself is primarily a transformer that handles tokenization, mapping, and neural-network reasoning (in simple terms). It's the engine. It takes in language, interprets it's meaning, and based on other language that supplies instructions, decides how to respond. The agent typically takes the form of an instruction for how to use a tool, combined with how to access it.

Technically, the chat session is itself an agentic tool because it's taking input and returning output through that interface. But it's kind of the default tool. Stdout, if you will.

Say you're in Gmail and you get a message that tells you about a meeting, but doesn't include an invite. If you tell Gemini to add an event for that meeting to your calendar, the LLM interprets your instruction, then uses an agent tool to read your email, interprets it, and then uses another agent tool to create a meeting on your Google Calendar.

From an editing perspective, this went mostly down to a) attributing the change to a model rather than the harness and b) vibes.

In my mind no; an agent is an llm wrapped in more software (most trivially a while loop, but probably more then that)