the terms are used interchangeably. Some people believe that when fate points its fickle finger at you, it is said that 'what was meant to be was meant to be' and if it was meant to be it will happen no matter what you do. Destiny is understood as being (likeWystan said) where you end up but you don't control it anymore than with fate! see what I mean? Of course, some people believe they control their fate/destiny. That life is not a set of chance events but of choices. So! Do you control your destiny or does fate control you? What do you think?

That's a tricky question. There isn't really much difference between them, and you can use either in most cases, but, in general, "fate" is said to determine everything that happens in life, whereas "destiny" simply determines where you will end up.