How is Anne Frank different from other teenagers?
On some levels, as we see from her writing, Anne Frank has many average tendencies. She tends to be full of romantic ideas, combative with her mother, secretive, and silly.
Yet, in some part due to her seclusion, she is highly insightful of the human condition for her age. In July of 1944 she wrote, "I feel the suffering of millions." and this is certainly not the commentary of the average teenager.
Anne's circumstances led her to observe the interrelationships of those forced to live in close quarters and draw conclusions from it. Without the interactions with friends and being in the real world, Anne had a lot of time on her hands. She seems to have been naturally introspective, and with the situation, she examines her feelings and the actions of others in depth.
Most teenagers have many distractions that would keep them from such soulful scrutiny.