₪₪₪ How could 2 people both working at the same place, 1 made $200 more, & gets back over $8000 more in taxes?

My fiancee and his friend work at the same place. His friend made only $200 more than my fiancee and my fiancee is getting back only $1900 back in taxes and his friend is getting back over ten thousand! How could this be? His friend is married with 2 children. That is the only difference.