When you are talking about a way in which two people or things are different, use the pattern a difference in something (not ‘difference of’ or ‘difference about’):
✗ There is a big difference of grammar between Japanese and English.
✓ There is a big difference in grammar between Japanese and English.
✗ There are major differences about language and customs in various areas in Korea.
✓ There are major differences in language and customs in various areas in Korea.
You can use difference of with a number or percentage, when you are talking about the amount by which two things are different:
He secured 50.7 per cent of the vote against 49.3 per cent (a difference of 227 votes).
Difference of is also used in the phrase difference of opinion which means ‘a disagreement’:
On this issue there is a major difference of opinion between the British government and most business leaders.
Don’t use the expression make a difference to mean ‘recognize that two things are different’. Use make/draw a distinction:
✗ Children cannot always make the difference between fiction and reality.
✓ Children cannot always make the distinction between fiction and reality.
The expression make a difference (to) means to have an effect on someone or something, often a positive effect:
Changes to the age of retirement make a difference to the amount of savings people need.