Django Unchained and Inglorius Basterds are both set in the same alternative history universe according to Tarantino. How many of the films made by Tarantino are set in the same universe? Are any of the films he's wrote or starred in but not directed set in the same universe?
Tarantino is an odd figure, creating actual Universes for each of his characters that all tie into one another somehow.
They are broken up in a few categories including the Realer than Real Universe which include his history-altering pieces like Basterds where these people are supposed to be living in a real world, as in the way Hitler was offed in this Universe, as far as the people in Pulp Fiction are concerned, actually happened.
The first evidence of this was brought on with a connection between Pulp Fiction and Reservoir Dogs where we have the Vega brothers, Vic and Vincent. Also, as a subtle hint, this image shows the connection between Pulp Fiction and Django Unchained with Captain Koons.
Then, we have what he refers to as the Movie Movie Universe where these movies are movies that the characters in his Realer than Real Universe can go see at their local theatre.
An interesting theory that has come of this is that Mia Wallace from Pulp Fiction could actually be playing The Bride - Beatrix Kiddo in Kill Bill, as she did attempt an acting career before and the Fox Force Five failed pilot has a lot of similarities to Kill Bill
In a matter to complicate things, it has been stated that he has characters than can crossover these borders to be in both universes; supposedly Winston Wolf as well as a lowly guard Earl McGraw meet this criteria.
Finally, we have Jackie Brown which apparently doesn't meet any of these criteria and is in it's own universe called the Elmore Leonard Universe. It seems this is set in its own universe because it was an adaptation of someone else's work, therefore it is set in its own universe entirely for this reason.
Explained rather briefly but still effectively in this little wiki page it states simply that
Are all a part of the Movie Movie Universe
This image, shows a great visual connection of all these movies...though it is a bit outdated.