make a difference
1. To have some effect on something; to cause a change. Will it make a difference if I add the salt before or after I heat up the soup? I don't think it will make a difference if we're five minutes late.
2. To have an impact, especially in a positive way. Graduates, you can make a difference in this world. You can reshape the future! He probably doesn't know it, but his kindness to us as kids really made a difference.