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Fine-Tuning vs Prompting

AI & ML: lesson 13 of 15

Change the instructions, or change the weights.

Lesson 13 of 15 · 5 min

Fine-Tuning vs Prompting

Step 1 of 13

Prompting steers a frozen model with instructions supplied at request time.

The Idea

Prompting steers a frozen model with instructions and examples supplied at request time. Fine-tuning continues training on your own examples so the behaviour is baked into the weights. One is instant and reversible; the other is neither.

Real-World Example

Airline cabin crew. The safety card is read out every flight and can be reprinted overnight. Recurrent training reshapes reflexes instead — weeks of work, and no memo can undo it by tomorrow.

The Tradeoff

Fine-tuning buys consistent formatting, shorter prompts and lower cost per call. It charges you dataset curation, a training run, and a model version to maintain and redo on every base-model upgrade. Prompting and retrieval are almost always the cheaper first attempt.

Your turn

Put the steps in the right order.

  1. Fine-tune on curated examples, but only if the gap survives everything above
  2. Write a clear prompt with a few worked examples
  3. Add retrieval if the failures turn out to be missing facts
  4. Measure where the output actually falls short

Mini quiz

1 / 3

Fine-tuning is best suited to: