Its in Episode 3 that the Leia qualities come out. Compare Anakin in rescuing Palpatine, 'Always on the move'. He's in the lift and rather than wait it out he's scanning the environment and trying to find a way out. He puts a hole in the roof and jumps out. Its not that different from Leia's uneasiness when she's just out of the detentionary. They are stuck and at the mercy of the enemy so she grabs a gun, shoots a hole in the garbage shoot and does the slip and slide down it. She's quick thinking and quick witted, that is Anakin. Luke is a more careful planner. He'll jump into situations like Anakin but he'll think those situations through more. In rescuing Leia he doesn't go shooting the stormtroopers and barge his way in like Anakin would. He sneaks. Compare Luke using a stormtrooper outfit to infiltrate the detentionary using Chewy as a faux prisoner with Padme planning her forces to infitrate the palace of Theed disguised as a the queen's decoy. That takes thought and patience. The nearest we see Leia do that is when she is presenting the plans to the troops but its very unlikely they were her own rather than what more senior figures in the alliance had agreed upon. We see the difference again in Return of the Jedi. Leia is the one in the battle using her sharp mind to its best advantage especially when the plan goes awry. Luke surrenders to the Empire knowing he will be taken to Vader so he can pursue a non violent solution to getting to his father. Palpatine is drawing the Anakin out of him because it is there but its not strong enough. Palpatine is using the same traps he used with Anakin thinking father and son have the same trigger and underestimating Luke the same way he underestimated Padme.