As many avid Harry Potter fans can tell you, there are many differences between the books and movies. We understand that they can't fit every little detail from the novels into the films, but there is always room for improvement. Seeing as Harry Potter and the Sorcerer's Stone is the shortest book, they didn't leave out too many of the important details, but there are definitely some that stand out. An example of this is when Harry and Hagrid are shopping in Diagon Alley, Harry has his first encounter with Draco Malfoy. He's pompous and entitled, of course, but they don't hate each other yet, granted they don't know who the other is yet either. Another thing the movie skips is that after Harry and Hagrid's day of shopping, Harry has to go to back to the Dursley's for about a month before school at Hogwarts starts. In the movie, Hagrid drops Harry off at the train station right after  they spend time in Diagon Alley in the film. A couple more small differences are Neville, Ron, and Malfoy get into a fight during the Quidditch match, and in the Mirror of Erised Harry sees his entire extended family, as well as his parents. These can be found in the book but not the movie. The one difference that irritated me the most, was when Harry and Hermione need to figure which potion to take when they going after the stone. This part of the book always intrigued me, and I would reread it over and over to see if I could figure it out on my own. Hermione was my idol. This part isn't in the movie at all! 

All in all, the filmmakers didn't so too bad of a job fitting the details into the movie. As the books get longer and more detailed, the movies get worse. But you'll see when I compare each and every one!