Well, it’s really rooted in the difference between the types of girls that go to each seminaries. Bnos Sarah is populated by the mainstream-yeshivish, cerebral aidel type. Machon Raaya specifically caters to the out-of-town, intellectually curious (read: sometimes get into very…lively discussions with teachers), like-to-have-fun type. That really makes the two have crucial differences in their respective approaches to teaching and academic missions.
(We’re actually having a Shabbaton reunion thingy and my friend is sitting next to me and yelling at me to “stop being so anti-social.” But she’s also helping me phrase this response. So thanks, friend. 🙂 )