They are different parts of speech. 'Because' is a conjunction. It is followed by a phrase containing a subject and a verb. What follows 'because' is a mini-sentence in itself. The match was cancelled because [it was raining.] They stayed home because [the weather was bad.] We left the party because [John was rude to us.] 'Because of' is followed by a noun or noun phrase. This is because 'of' is a preposition. The match was cancelled because of [the rain] They stayed home because of [the bad weather] We left the party because of [John's rudeness]. I hope that helps.

1)e.g. I lost my job because you didn't help me. (Because you didn't help me, I lost my job) 2)eg. I lost my job because of you. (Because of you, I lost my job)

because + sentence or because of + noun, sentence