<p>They certainly do, at least enough that you will not get away with applying to both SCEA.</p>
<p>Yale is not “much much more” undergraduate-focused than Harvard is; I don’t think there is, to be honest, all that much difference between the two as wholes that isn’t hair-splitting. (At the level of departments, if you know your major, or main extracurricular, if you know that either, there are sometime significant differences.) However, if you have visited both schools and feel that Yale is so much more undergraduate-y, go to Yale. When I visited Princeton junior year, I was like, Oh my God, this is terrible and atrocious. Still don’t really know why. Is Princeton terrible and atrocious? Of course not, but if I felt that way and went there, I would not have been happy. I get that you’re more ambivalent than I was, but confirmation bias is a powerful force…I, at least, would’ve seized on the flaws to be like “see! I was right!” If you haven’t visited both schools and can manage to do that, that would probably help 
And you can always apply to the other regular.</p>