Sahana, there are several possible reasons why someone could be admitted to a "top 5" school such as Kellogg and dinged from a "top 15" (maybe top 10?) school such as Yale SOM....
1.) Great fit at the higher ranked school & poor fit at the lower ranked school.
2.) Too many applicants with your profile already admitted to such a small class at the lower ranked school. You listed Social Enterprise as your concentration. I'll bet that Yale, which is great for non-profits, received many applications from people with that particular background. As far as I know it has the smallest class out of all top 15 schools.
3.) Far superior performance on the essays and the interview for the higher ranked school. (I'm pretty sure this is why I was admitted to Kellogg and dinged at Tuck

)
I actually applied to Yale in R3 but withdrew after learning of my Kellogg admit.