How does an INNER JOIN differ from a LEFT JOIN in SQL?

Short answer: INNER JOIN: Returns only the rows that have matching values in both tables. LEFT JOIN (or LEFT OUTER JOIN): Returns all rows from the left table and the matching rows from the right table. If no match is found, NULLs are returned for columns from the right table.

Real-world example (ShopNest)

An invoice query INNER JOINs Orders and OrderItems, and LEFT JOINs Discounts so orders without a coupon still appear.

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.