Is it harder to get into Harvard early action than it is to get in regular decision?
^^ It really depends on an individual student’s stats, as I don’t think you can make one general statement about the SCEA round being harder or easier that pertains to all students.
SCEA is not for every student – it is SUPER competitive, meaning the best-of-the best student’s tend to apply early, and that’s true whether you apply to Harvard, Yale, Princeton or Stanford.
IMHO, if you have an SAT score in the 99th+ percentile (or the ACT equivalent), with lots of AP classes and AP tests (with all or mostly 5’s) and an unweighted GPA above 95 (on a 1-100 scale) or an unweighted GPA of 3.9 (on a 1-4 scale), and are ranked in the top 1% to 3% of your graduating class, then you should apply to HYP or S in the SCEA round. Pick a school, whichever one is your favorite, and apply, as the odds tend to be better (and easier) for HIGH-END student’s in the early round, no matter what Admissions says otherwise.
If you have an SAT or ACT scores below the 99th percentile, and are ranked in the top 4% to 10% of your high school’s graduating class, then you should NOT apply SCEA, as there is a high probability that your application will get buried by the polly-perfect’s of this world, and there is a high probability you will be deferred. Instead, student’s who have scored below the 99th percentile in the ACT or SAT and who are ranked in the top 4% to 10% of their graduating class should apply to a broad range of non-binding colleges early and apply to HYPS in the RD round.