The thesis of determinism is that the laws of nature fully determine everything that happens. Every state and event is determined by prior states and events.
Fatalism is different in that it is based on our fate being pre-determined and not based on particular actions or the current state of the physical world.
Some forms of determinism allow for human thought and decision making to affect the outcome.
In a deterministic world what we do is determined by the laws of nature. This can include human actions and reactions to external events. There are a number of interpretations of determinism and whether this allows for free action:
Soft Determinism - compatiblists believe free action is possible in a deterministic world
Libertarian - the belief that there is free action and so the world is indeterministic
Incompatiblists - the belief that there can be no free action in a deterministic world
Hard Determinism - the belief that determinism precludes any free action