Four years older than his sister Scout, Jeremy "Jem" Finch seems to have a deeper understanding of the events during the three years of the novel, for his emotional reactions to them are stronger.
Jem and Scout are both mature children. This is due to the fact that Atticus treats them maturely. Both Jem and Scout are interested in the Robinson trial. They attend the trial and pay close attention to the details of the trial. While some children would not take an interest in their father's occupation, Jem and Scout find Atticus' work extremely interesting.
Jem and Scout both revere, deeply respect, their father. They try to please him. Jem especially does not want to disappoint his father:
He is anxious to please his father, and hates to disappoint him.
While Jem and Scout are mature for their ages, they also enjoy role playing. They pretend to be the Radleys. They reenact the stories they have heard about the Radleys. Jem and Scout are very much alike when it comes to role playing. They enjoy the drama. Scout is a tomboy who proves she is just as equal to Jem:
A tomboy most frequently clad in overalls, Scout spends much of her time with her older brother Jem and is constantly trying to prove herself his equal.
No doubt, Jem gets frustrated with Scout, but he allows his sister to play the games he and Dill enjoy. Except for when they are at school, Jem acknowledges Scout and treats her like one of the boys:
Jem is frequently exasperated by his sister, and requires her to keep her distance during school hours. Nevertheless, for the most part Jem is an understanding and encouraging older brother, allowing Scout to join in his games and even dignifying her with an occasional fistfight.
As the story evolves, Jem grows up more so than Scout. This is when the differences become evident. Jem desires to go swimming with Dill. He leaves Scout behind. Jem is beginning to realize that Scout is girl. He desires to just hang out with Dill, keeping it among the boys. Jem begins leaving Scout out of the activities. He is also becoming too mature to role play. He loses his fascination with the Radleys. He does not desire to play games as he had been used to playing when he and Scout were younger.
As Jem reaches adolescence, he becomes quieter. He finds the guilty verdict shocking during Tom Robinson's trial:
Although more socially aware than Scout, he is genuinely surprised at Tom Robinson's guilty verdict. The trial leaves Jem a little more withdrawn and less self-confident, and he spends much of the following fall concerned for his father's safety.
Truly, Jem is growing up. He is more aware of the seriousness of the trial. He is forced to accept the injustices that occur in Maycomb. Scout is still quite young and not as socially aware. While she does realize that some folks are discriminated against, she does not fully understand why all folks are not treated equally. To Scout, folks are just folks.
Jem is beginning to understand the harsh reality of discrimination. He realizes how wrong it is to discriminate. He realizes how dangerous some people are when he faces the attack by Bob Ewell. Jem steps up and tries to protect his sister.
They are both kids who have the same father and relatives the difference is that Jem is growing up which is leaving Scout vunerable another is that Scout is very troublesome and Jem is sensitive, Scout is careful Jem takes risk so these are some difference that i have noticed in the book so far.