When you choose a scale at which to operate, it dictates the amount of precision that you can use. Scale and precision are related. On a software development project, these terms have analogous meanings and uses. Every deliverable, from requirements to project plan to hardware and software design, can be described at various scales, to varying precision, with varying accuracy. You get inappropriate discussions if you try for inappropriate precision, accuracy or scale.
Precision is the most significant of the three.
It declares the amount you care to say about a particular item, and therefore it controls how you work on the project. Most deliverables have three or four useful levels of precision. For the project plan , The first level of precision is to state the releases, what basic functionality is in each, and the development dependencies between them. The second is to state which functions are in each release, which team is developing each, the specific dependencies between the teams and the delivery dates. The third includes milestones and the due dates for each deliverable involved in the release.