As can mean because and is used when the reason is already known by the person being spoken to, or when the as clause is not the most important part of the sentence.
Examples:
As it was very late, we drove straight to the hospital.
As last weekend was so wet, we didn’t go hiking
In less formal English, so is often used to express the same idea
Examples:
The door was open so we walked straight in.
As the door was open, we walked straight in
Since
Since is used in the same circumstances – when the reason is already known by the listener. Likewise it is usually used at the beginning of a sentence.
Examples:
Since we have no time today, can we talk about it in your next session?
Since we are going to be working together, it’s better that we get on.
Because
Because is used when the listener is unaware of the information. The because clause is also of more importance in the sentence..
Examples:
Because I was always late for work, they gave me the sack.
If the information in the because clause is the most important part of the sentence, that clause will be placed at the end. (As and since cannot be used in this way.)
Examples:
”Why do you want to know where I was? “ “I want to know because you were supposed to be at home with me.”
I know where you hid them, because I found them in your desk.
For
For is used to introduce new information, but the reason is secondary in importance – almost an extra which could be excluded. These clauses always go at the end of the sentence. It is quite formal.
Examples:
They decided to find a hotel , for it was quite late.
Whereas like is used to compare things.
Examples:
She drives like a lunatic. (She isn’t really a lunatic)
Your room is like a pig sty. (It isn’t really a pig sty.)