I literally majored in both IOE and CSE and I can confirm that IOE is easier.
I’m sure that there could be some test that could determine by some reasonable definition of “harder” which is indeed harder. Since no such test has been conducted as far as I know it’s hard for me to defend my position with anything more than “I did both and I say so” but you can take my experience as indicative as what you would experience or not.
For what it’s worth I wasn’t Summa Cum Laude (though I wasn’t too far off) but Nubs was.