For selective schools, the difference in acceptance rates between Early and Regular applicants can be quite significant. Here are the Ivy League statistics for Class of 2020 starting in Fall 2016:

Brown – ED 22.1% vs. RD 7.66%
Columbia – ED 17.6% vs. RD 4.8%
Cornell – ED 27.4% vs. RD 12.5%
Dartmouth – ED 25.6% vs. RD 9.0%
Harvard – REA 14.9% vs. RD 3.4%
U Penn – ED 23.9% vs. RD 7.0%
Princeton – REA 18.6% vs. RD 4.7%
Yale – REA 17.0% vs. RD 4.4%