At Hogwarts, Harry would have a different perspective on the Houses. Since he grew up with James and Sirius, both Gryffindors, he might have a stronger sense of Gryffindor pride from the very beginning. He might also be more critical of other Houses, or at least have a more one - sided view. His experience in Quidditch would also be different. James was a great Quidditch player, so Harry would have had more training and might be an even better player right from his first year. He could also be more involved in the Gryffindor Quidditch team's management and strategy, as he would have grown up hearing about James' Quidditch feats.
Harry would probably have a different attitude towards Hogwarts rules. Since James and Sirius were known for their rule - breaking at Hogwarts, Harry might be more inclined to bend the rules. He could be involved in more pranks and might not be as afraid of getting into trouble. Also, his relationship with the teachers would be different. Some teachers who were friends with James and Sirius might be more lenient with Harry, while others might be more strict because they expect him to live up to his father's reputation. His experience in the Gryffindor common room would also be different. There would be more stories about his father and Sirius, and he would be part of that legacy from the start.
His Hogwarts experience would be very different. Firstly, he would likely enter Hogwarts with a much higher level of magical knowledge. James and Sirius could have taught him a great deal before he started school. So, he might be ahead in classes like Transfiguration and Defense Against the Dark Arts. Secondly, his social status would be different. Everyone would know he is the son of James Potter, a popular and talented wizard. This could lead to him being more of a center of attention, and he might have a different group of friends. Instead of Ron and Hermione at first, he could befriend students from more well - known wizarding families.