They are both prepositions, "owing to" is just a different way of saying "due to"
I'd use "due to" or "because of" they are more commonly used, have better flow and can be used more often. Just remember not to use because (on it's own) as a sentence starter.
While I'm on the subject:
Both owing and Due can mean the same thing in a sentence they are highly context sensitive though.
Ex: You can owe someone but you can't due someone.