All in the perspective
B: Mom, my teacher has this book, but her cover looks different.
Me: Yes. Your teacher has a newer copy of the book. This cover is different, but the pictures and words are the same inside. Your mom just has an older book because she's a little bit older than your teacher.
B: No, no, Mom. That's not true...
Pause for dramatic effect
B: You're A LOT older than my teacher.