Business analysis artifacts work best as a connected set rather than as templates completed in isolation. A BRD, an FRD, and a user story can all be useful when each one answers the right question for the work at hand.
The business requirement document
A BRD focuses on the business need. It helps communicate the problem, goals, stakeholders, scope, and high-level context. It is useful for keeping the work anchored to why a change is needed.
The functional requirement document
An FRD adds detail about the expected functional behavior. It can describe process flows, inputs, outputs, rules, roles, dependencies, and conditions that a delivery team needs to understand.
The user story
A user story brings a requirement into an Agile delivery context. It describes a user, their goal, and the value they seek. Acceptance criteria make the intended behavior testable.
A connected approach
The artifacts should reinforce one another. The business context explains the reason. The functional detail explains the expected behavior. The story and criteria support planning, discussion, and validation. The amount of documentation should fit the complexity of the change.