My macbook pro has no battery life left, I lost the charger and only have my sisters MacBook charger! Will it charge my macpro??
MacBook Pro? No, it won't.
The MacBook and MacBook Pro chargers are interchangeable.
They're not. The MacBook charger cannot draw enough power to keep a MacBook Pro charged while it is in use. It MIGHT be able to charge it when it is off or asleep, but you cannot use it plugged in.
They are still interchangeable.
You keep using that word. I don't think it means what you think it means...
YES, the PLUGS are interchangeable, but I'm saying that since one is 60w and the other is 85w, you can't keep the battery of a MacBook Pro charged with a MacBook adapter while using the computer, so the only good comes with the computer off.