Mustafar was a small volcanic planet located in the Mustafar system, situated between two gas giants in the Outer Rim Territories. It was where Obi Wan defeated Anakin and therefore he became Darth Vader.
Tatooine was a desert planet located in the Outer Rim Territories. Tatooine was the homeworld of Anakin Skywalker, the Chosen One, and his son Luke Skywalker. Anakin's former master, Obi-Wan Kenobi, also resided on the planet.