If your definition about 'conventional' construction project is the project that uses a 2D CAD drawing tools, then there are huge differences in terms of time, cost, quality, productivity, and design. But for simple design or small projects, the difference is negligible.
By using BIM in construction, the following benefits are attained:
More Detailed Visualization Tools: Architects can see the building in basic 3D dimensions like height, width, and depth. But BIM also enables us to view a building based on how long it will take to complete each element (4D) and how much it will cost at every stage (5D).
Time conservation: Most effective to define a renovation area within limited timespace.