Because of vs. Due to

What is the difference between because of and due to?

Because of is a preposition used to introduce an adverbial phrase and means “as a result of." It is not used after after a form of the verb to be.

For example:

- She had a headache because of the enormous elephant peculiarly perched on her head.

Due to is a predicate adjective + preposition that means "the result of" or "resulting from." It is always used after a form of the verb to be.

For example:

- Her headache was due to the enormous elephant peculiarly perched on her head.

Due to has to follow some form of the verb to be.

Reference:

[1] http://linguistech.ca/Tips+and+Tricks+-+Because+of+vs.+Due+to