There is a difference. Luck does not have any substantive connection between effort and results. Being fortunate implies at least some sort of effort was made and success came, not out of the blue (completely) but in part from the effort put into the activity.
The media (especially sports writers) use the term luck when the result of the contest seems to be determined by some fluke bounce, bad conditions or some other random event. But is this a fair and balanced view of cause and effect? Does the result of the sporting event really swing on one seemingly insignificant turn of events? What about all the activity that occurred before that event, does that not count? Of course it is more dramatic to point to one event (say a Cub’s fan interfering with an outfielder) when a more balanced view would be more fair and just. But drama makes for a better story and “sells more newspapers”, when people bought newspapers.
And of course whether you are on the winning side or the losing side effects the perception of whether you think you were lucky or fortunate or neither. One man’s luck is another man’s…fortunosity.