That's different; it's like comparing The Lord of the Rings to The Departed or No Country for Old Men.
They are so different in their own amazing ways, that I can't even begin to explain. Battlestar Galactica is a long epic journey, that hit every emotion it possibly could, and makes you think about things beyond the show, and Dexter is a series of twisted, and dramatic events strung together in a masterful fashion.
That's the best I can do to describe it.