Below are the differences I could find between the British and American editions of Harry Potter and the Philosopher's Stone.
Of course, the first difference is that the American title is Harry Potter and the Sorcerer's Stone. In addition, I have not flagged every instance of
| British | American | British | American |
| Page/Line | Page/Line | Text | Text |
| ========= | ========= | ==== | ==== |
| 7/8 | 1/8 | moustache | mustache |
| 7/11 | 1/11 | neighbours | neighbors |
| 7/21 | 2/6 | neighbours | neighbors |
| 7/26 | 2/11 | gray | grey |
| 8/26 | 3/14 | get-ups | getups |
| 8/36 | 3/24 | car park | parking lot |
| 9/7 | 4/7 | lunch-time | lunchtime |
| 9/8 | 4/8 | baker's opposite | bakery |
| 9/24 | 4/23 | dialling | dialing |
| 9/26 | 4/26 | moustache | mustache |
| 10/38 | 5/9 | realised | realized |
| 10/1 | 5/12 | passers-by | passerby |
| 10/19 | 6/2 | behaviour | behavior |
| 10/24 | 6/7 | Shan't | Won't |
| 10/26 | 6/9 | living-room | living room |
| 10/34 | 6/17 | news reader | newscaster |
| 10/40 | 6/23 | Yorkshire | Yorkshire, |
| 11/18 | 7/13 | lot | crowd |
| 12/19 | 8/26 | bright | bright, |