make a difference in
make a difference in (someone or something)
1. To effect a specific change in someone or something. It won't make a difference in our estimated date of release, but I think this new production method will end up saving us a great deal of money in the end. Our new advertising campaign hasn't made much difference in the numbers of people coming to the shows.
2. To make a significant, typically positive impact on someone or something. Graduates, each and every one of you can make a difference in this world. You can reshape the future! I can tell that the counseling has made a difference in Tom—his mood and behavior have been much better recently.
make a difference in someone or something
to cause a noticeable change in someone or something. Getting a job made a big difference in my lifestyle. His mother's death made a difference in his attitude toward doctors.