Introduction:
In the story "The Fun They Had" by Isaac Asimov, Tommy and Margie are the main characters who live in the year 2157. They are both students, but there are several differences between them.

1. Age:
- Tommy is a thirteen-year-old boy, while Margie is an eleven-year-old girl.
- This age difference implies that Tommy is slightly older and possibly more mature than Margie.

2. Attitude towards school:
- Tommy is not as interested in school as Margie is. He often finds it boring and prefers to play outside.
- Margie, on the other hand, enjoys school and is eager to learn. She is diligent in completing her assignments and is disappointed when the school is closed for maintenance.

3. Academic performance:
- Margie is a diligent student who consistently performs well in her studies. She is praised by the County Inspector for her progress.
- Tommy's academic performance is not explicitly mentioned in the story, but his disinterest in school suggests that he may not perform as well as Margie.

4. Technological proficiency:
- Margie is shown to be more technologically proficient than Tommy. She knows how to operate the mechanical teacher and is familiar with the concept of books and reading.
- Tommy, on the other hand, struggles with reading and finds it difficult to comprehend the printed words in the book.

5. Reaction to changes:
- Margie is initially excited when the new teacher, Mr. Smith, is introduced. She looks forward to learning from a human teacher instead of the mechanical one.
- Tommy, however, is skeptical of the human teacher and expresses his preference for the mechanical teacher, as it was easier to fool.

6. Gender roles:
- Margie is a female character, while Tommy is a male character. Although their gender does not play a significant role in the story, it is worth noting that Margie is portrayed as a diligent student who enjoys learning, while Tommy is more inclined towards outdoor activities.

Conclusion:
In summary, Tommy and Margie differ in terms of age, attitude towards school, academic performance, technological proficiency, reaction to changes, and possibly gender roles. These differences contribute to their unique characters and experiences in the story "The Fun They Had."