The correct contrast between Federalists' and Anti-Federalists' understandings of what a bill of rights would do in the Constitution is:
Federalists saw a bill of rights as a document that would limit people’s rights, while Anti-Federalists saw such a document as preserving the most important rights.
This reflects the Federalists' belief that a bill of rights was unnecessary and could even pose a risk of limiting rights, whereas the Anti-Federalists argued that a bill of rights was essential to protect individual liberties against potential government overreach.