[make] (a|the) difference

to have a very strong and noticeable effect on someone or something

Volunteering at the local shelter can make a difference in the lives of homeless individuals by providing them with food and shelter.
A little sympathy makes a world of difference to someone who's been badly treated.
Small acts of kindness, like helping a neighbor with their groceries, can make a difference in building a strong sense of community.
Adding a fresh coat of paint to the room made a world of difference in brightening up the space and giving it a more vibrant atmosphere.
Every donation to the charity makes a difference in supporting critical medical research.