Answer

Use Cases describe a step-by-step sequence of actions between a user and a system to achieve a result; they are used for complex processes that require detailed elaboration. User Stories capture the user's wish for the outcome through a brief formula (As a... I want... So that...), suitable for flexible, iterative projects. User Flows visualize the navigation or path a user takes through the system, often in the form of a diagram with transitions between screens.

Key features:

• Use Case: focus on complete process elaboration, error scenarios, alternative branches.
• User Story: conciseness, focus on user value and goal.
• User Flow: visualization of action sequences for UX analysis.

Application:

• Use Case: complex business processes with a variety of scenarios.
• User Story: Agile projects, tasks for iterative development.
• User Flow: interface design, prototyping.

Tricky questions.

Can all use cases be replaced with user stories in any project?

No, user stories are too brief for complex scenarios. For broad processes with multiple alternatives, they would be difficult to maintain.

Does a user flow necessarily require software tools for visualization?

No, often a simple hand-drawn diagram is sufficient — the structure is important, not the complexity of the tool.

Should user stories contain only wishes, or also acceptance criteria?

Acceptance criteria are definitely needed — without them, the user story will be incomplete and non-functional.

Common mistakes and anti-patterns

• Using only one format of documentation for all tasks.
• Describing a complex process with overly short user stories.
• Lack of visualization when it is necessary for understanding navigation.

Real-life example

Negative case: In a large project, all processes were described only with user stories and alternative scenarios were not captured. Pros: Quickly created a backlog. Cons: Developers did not understand all the conditions for transitions between steps, leading to unpleasant bugs in production.

Positive case: Implemented use cases for complex processes, user stories for simple tasks, and user flows for navigation. Pros: Ensured complete coverage of requirements, minimized risks. Cons: The documentation process took more time.