If you are not familiar with the game, it has two game modes... playset and toy box.
Playset mode allows you to play the characters through a story... like many other video games. You can play as either character that comes with this set or other Star Wars characters that are a part of the storyline (Yoda or Obi Wan). You can play as other Star Wars characters during the fight scenes too in some cases (e.g. fight Darth Maul with Darth Maul), but not play the story itself.
In Toy box mode, you play your characters in open areas that you can build. There are predesignated minigames or you can create your own. The cool thing is that in this mode you can play ANY characters with each other... including any from Infinity 1.0 or 2.0. Like have a race between Captain America and Darth Maul. It is like playing with real toys... you can do whatever you can think up.
The only downside is that you can only play with two characters at a time in either mode. There is a battle mode playset that is sold separately (comes with 3.0 Captain America) that allows you to play up to four characters.