What's the Difference Between Because and Because Of

Because and because of have the same meaning, which is to introduce a reason. The difference is how we use them. Yeah, it's a grammar issue. 

We use because (without of) followed by a subject and verb. In other words, the pattern is because + a sentence. The tense of that sentence doesn't matter - you can have a past, present, or future sentence after because.

• Because it was getting late, I went home.
• Tom must be leaving the office because he’s putting on his jacket.
• I like that restaurant because the food is good and the prices are reasonable

We use because of plus a noun. Like because, when because of comes at the beginning of the sentence, use a comma after the clause containing because of. When because of comes in the middle of the sentence, you don’t need a comma before because of.

1. Because of the rain, we cancelled the picnic.
2. Because of the time, I went home.
3. She was unable to eat the cake because of her diet.

Be careful about one point. Don't use because of plus a time word. For example, you can’t say, “Because of October, the weather is getting cooler.” Instead, you can say, “Because it is October, the weather is getting cooler.”