The speaker feels different from everyone around her, and the poem circles that one idea, ending nearly every stanza on the words "i'm different." At home, she sees herself as the forgotten sister, someone who looks and thinks differently from her family. She lists her curvy figure, honey brown eyes with yellow rings, and freckles, then offers her best image: a maple tree growing among oaks. It's a gentle comparison that suggests she isn't wrong or broken, just another kind of tree.
At school, the feeling turns into hiding. She copies everyone's habits, and the quick list of "walking / talking / eating / drinking / believing" makes this feel like a performance. Underneath is a mind she thinks is complex and a set of emotions kept behind a locked door. The mood is lonely and anxious, but also quietly proud. She believes she is different "in a good way," yet fear of being found out leaves her unable to finish her sentence at the end, as if even saying it is risky.