What is the difference between “difference between” and “difference in”?

Use “difference between” when comparing two or more complete things.

Use “difference in” when talking about a specific feature, quality, amount, or area.

Examples:

• What is the difference between coffee and tea?

• There is a difference in taste.

• There is a difference in price.

• The difference between the two plans is small.

A simple rule:
Between compares the things.
In points to the area where they differ.