What is the difference between a 401 and 403 status code?

Short answer: 401 Unauthorized → Authentication required (client not logged in / invalid token). 403 Forbidden → Authentication is valid, but the user lacks permissions.

Real-world example (ShopNest)

Creating an order is POST /api/orders → 201 with Location header. Fetching is GET /api/orders/{id} → 200 or 404.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.