Harry Potter and Neville Longbottom each grew up to be a crucial part of the wizarding world. Harry was already famous as the Boy Who Lived. Everyone had known his name and thanked him for defeating Lord Voldemort. However, Harry didn't understand how or why Voldemort had been after him. It wasn't until after Sirius died that Harry learned the true nature of why he was so significant to Voldemort.
At first, and for many years, Neville was a kind but forgetful person. He was not great in Potions or Transfiguration and did not have the best track record with magic in general. Part of this came from using his father's wand instead of one that chose him. When Neville got his own wand, he began to improve. Yet, Neville's most essential changes would not occur until his seventh year. Harry, Ron, and Hermione are reunited with a stronger and more intense Neville Longbottom. Harry and Neville were each vital to the overall story, and they had many similarities and differences.
Similar: Their Parents
James and Lily Potter served in the Order of The Phoenix alongside Frank and Alice Longbottom. The four were part of the organization wishing to defeat Voldemort. They had all been in Gryffindor as well. The two couples faced Voldemort during their lives.
When Harry and Neville attend school, James and Lily are remembered for their deaths leading to Voldemort's demise. Meanwhile, Neville's reside in St. Mungos Hospital, having been tortured to insanity. While Frank and Alice got to keep their lives, they were never the same, and neither Harry nor Neville ever got to have a real relationship with their parents.
Different: Destiny
From the moment Voldemort decided to kill Harry, it would become Harry's fate to kill Voldemort. The prophecy stated that the one with the power to defeat Voldemort was a boy born at the end of July whose parents had thrice defied the Dark Lord. Although their destinies were different, Neville was very close to receiving Harry's.
It came down to the boy Voldemort marked as his equal, deciding to mark the Half-Blood wizard instead of the Pure-Blood. However, although Harry did defeat Voldemort with the final blow, Neville killed Nagini, taking out Voldemort's final Horcrux.
Similar: Gryffindor
Although Neville may not have believed he belonged in Gryffindor, he certainly proved his bravery by the finish. Both boys were sorted into Gryffindor going into their First Year. Their sorting showed not only the types of people they were but their values as well.
Harry was traditionally braver, jumping into danger to stop Voldemort. He was always more willing to put his life on the line. However, Neville showed his bravery in smaller ways. Neville was willing to stand up to his friends, and although Snape was Neville's greatest fear, he still showed up to Potions class.
Different: Confidence
One of the biggest differences between Harry and Neville for a majority of the franchise is confidence. Harry is not afraid to stand up for himself or others, doing so on numerous occasions. His boggart represents his biggest fear is fear itself.
Harry may not always be confident, but it is a more present part of his character. Neville, on the other hand, is frightened of nearly everything. He loses his toad, Trevor, constantly and hardly stands up for himself. It isn't until "Harry Potter and the Deathly Hallows" that Neville comes out of his shell.
Similar: Dumbledore's Army
Harry lead Dumbledore's Army during their Fifth Year to make sure that he and his classmates learned how to defend themselves from outside threats. Harry had watched Voldemort's resurrection and knew that the Dark Lord had returned even if the Ministry refused to believe it.
When Harry was on the run, Neville took up the mantle. Neville restarted Dumbledore's Army, stood up to the Carrows, and tried to recreate the feeling of hope Harry had inspired when he spoke back to teachers.
Different: Experience
When it came down to experience dueling dark wizards, Harry had more experience than any other student. Harry faced Voldemort and other dark wizards numerous times before the Battle of Hogwarts. Each year of school puts Harry's life in danger one way or another.
It was not difficult for Harry to have a leg up on his classmates in dangerous situations. Neville does gain more along the way, joining Harry at the Ministry of Magic to save Sirius. In the novel, Harry and Neville are the last two standing at the Department of Mysteries.
Similar: War Hero
After it was all over, Harry and Neville got to come out of the battle alive and as war heroes. Harry's title of The Boy Who Lived would forever be attached to him after killing Voldemort for the second time.
Harry, Ron, and Hermione had gone Horcrux hunting together, completing a mission only they were aware of. Although Harry would always be remembered for delivering the final kill, Neville played an integral role. Neville stood up against Voldemort when no one else did. He was deemed worthy of retrieving the Sword of Gryffindor from the Sorting Hat and used it to kill Nagini.
Different: Interests
Harry excelled in Quidditch and Defense Against the Dark Arts. He joined the Gryffindor Quidditch Team during his first year and continued to play, eventually becoming Captain. Harry later outshined others in Defense Against the Dark Arts, becoming good enough to lead numerous others in grasping defense spells.
Neville was more interested in Herbology. Unlike Harry, Neville enjoyed working with plants and better understand how they could be used. In Harry Potter and the Goblet Of Fire, Neville suggests Gillyweed for Harry to use during the Second Task. Neville does not give Harry the suggestion in the novel, but both of Neville's counterparts are interested in plants.
Similar: Harsh Relatives
Vernon, Petunia, and Dudley Dursley were awful to Harry. They kept him in a cupboard under the stairs for the first eleven years of his life and abused Harry instead of treating him as part of the family. While Vernon and Petunia despised magic, Dudley was a bully who hurt Harry at home and Muggle school.
Neville's experience was not the greatest, either, though. Neville's grandmother, Augusta, made a point to give Neville his father's old wand. Augusta compared Neville to Frank and Alice several turns, likely making Neville not confident in himself. Neville's family believed he could be a squib. His uncle had purposely placed Neville in danger to see if his magic would save him.
Different: Upbringing
Harry and Neville may have had similar issues with relatives, but they grew up in drastically different ways. Harry grew up in the Muggle World and was raised as a Muggle. He never knew magic existed and had been told his parents died in a car crash.
Hagrid's appearance in Harry's life is the first time he learns the truth about who and what he is. In Neville's case, he grew up knowing he was a wizard. Neville was raised surrounded by magic and knew the truth about his parents' situation.