One difference between blockquote and div is that a blockquote
cannot (if you want to comply with the standard[*], anyway) contain inline elements as direct children, it can only contain block-level elements.
So this is wrong:
Code:
<blockquote>Foo</blockquote>
but this is fine:
[*] I don't remember
which standard, it might have changed in newer ones, but epub 2 still uses HTML 4 something.