Plotwise it may as well be a different universe, but if you watch the movies you'll notice a lot of effort has gone into "synchronising" the lore of the game with the films.
The offhand comments of the characters are usually represented in the game, eg:
Obi Wan says - "the wastes of Jundland are not to be travelled lightly", and Jundland is one of the sub zones of Tatooine in the game, or Luke says he used to "bulls eye womp rats back home" when talking about the Death Star mission; womp rats being one of the mobs you fight there. Just two random examples I hit upon while re-watching A New Hope. They must have paid someone to sit through each film and make a list of all the random crap the characters come up with so they could fit it into the game