I didn't save any money. Now I'm broke. IF
If I had saved (some) money, I wouldn't be broke.
You can borrow my laptop provided you look after it. CONDITION
You can borrow my laptop on the condition that you look after it.
I'm going to go to the party. It doesn't matter if l'm invited or not. WHETHER
I'm going to go to the party whether I'm invited or not / whether or not I'm invited