What is the difference between Expensive and Costly? How to distinguish between Expensive and Costly. Let's see the following examples.
✗ This bike is costly.
✓ This bike is expensive.
✗ Buying all those old cars was a expensive mistake.
✓ Buying all those old cars was a costly mistake.
Expensive: Used for something usual, or regular buy or pay (expensive tickets, bikes, clothes etc)
Costly: Used for something unusual or rare that costs a lot (costly diamond rings) especially waste of money or cost a lot of money to correct or replace (costly mistake)