In Navisworks, two model can be compared at a time. First load the model and then append the other model using the Append tool. Next, select both the models in the Selection Tree window and choose the Compare tool from the Tools panel of the Home tab; the Compare dialog box will be displayed, refer to figure given below. Specify the options for finding the differences between two models by selecting the required check boxes in the Find Differences In area. You can configure the displayed results by selecting the required check boxes in the Results area and then choose the OK button; the results will be displayed in the Scene View.
In the Scene View the items highlighted with the red color will show the items with differences, white will represent the matching items, yellow will represent the first model containing the things not found in second model and the cyan color will represent the second model containing the things not found in first model.