Confused betewen reducers and dispatchers concerning actions

I'm a bit confused about reducers and dispatchers. Both will get actions as a parameter, but it doesn't mean that my dispatchers' actions are the same of my reducers actions, right?

Let say I have an action called fetchData, that action will be dispatch but won't reach the reducer since it doesn't modify the state.

All tutorials I read about redux, teach to set all the actions in one place. I think we should have reducersActions and dispatchersActions.

Am I missing something?