A wireframe is a low-fidelity representation that shows the layout and structure of a system’s interface but does not include interaction or functional features. In contrast, a prototype is interactive and allows stakeholders to experience simulated functionality.

Option A: Backend logic relates to system design, not wireframes.

Option B: Wireframes can include user input, not excluded.

Option D: A functional version is a prototype, not a wireframe.

Thus, a wireframe is distinguished by showing layout and structure without interaction.