Final answer:
Roberta and Twyla are different from the other children at St. Bonaventure's due to their strong friendship, their differing memories of Maggie, and Roberta's distinct appearance.
Step-by-step explanation:
Roberta and Twyla differ from the other children staying at St. Bonaventure's in a few ways. One difference is that they are inseparable friends, unlike the other children who may have different friendships. Additionally, Roberta and Twyla may have different memories and stories about Maggie, which sets them apart from the other children who may have similar experiences. Lastly, Mrs. Harvey's comment about Roberta's appearance suggests that she stands out physically, further distinguishing her from the other children.