I have one old dictionary that points out a subtle difference. A reliable person acts in a right and consistent way, like a good employee. A dependable person, however, is someone we go to for support and aid, like a good friend. Hope this helps.

There is no real difference both mean trustworthy. I might say my best friend is dependable and my car is reliable but others would say my best friend is reliable and my car is dependable both can be trusted. Use it as you want if you get a peculiar look from a native English speaker it may be your accent.

They are spelt and pronounced differently, lol

There reasonably interchangeable though it is somewhat more common to use reliability to refer to a machine and dependability for a human. That being said its certainly not written in stone.