Detail Level (Coarse, Medium, or Fine) is a per-view Revit display setting that controls how much graphical detail an element shows: a wall at Coarse might draw as a single line, the same wall at Fine shows every layer of its construction. LOD describes how reliable and developed the underlying model data is - a real, project-wide, cross-software concept. Detail Level is purely about how that same element is drawn on screen in one particular view, and has no bearing on the model's actual information content. A wall can carry full LOD 350 data and still display at Coarse detail in a small-scale site plan.