Click on 'Analysis' icon at top right while viewing a model.

It will expand to display available options.

Click on the last icon with two arrows in opposite directions to compare model revisions.

It enables you to compare model revisions by selecting the model files to compare based on doc ref and model discipline.

Clicking on the 'Compare' option will open a popup with options as shown below:

Document Reference - Displays model file's document reference.
First File (Base) - To select base revision that is to be compared.
Second File - To select the other (target) revision with which base revision is to be compared.

Select compare details as required using the corresponding checkboxes opposite the relevant Doc Refs and click 'Run' to continue.

Model comparison will start. You can track the percentage progress of the comparison once the comparison has started.

Once comparison is completed, comparison details will appear as follows:

The model object tree in the left, if open, will have only the comparison model objects enabled i.e. all objects from the base and target model revisions will only be available to select. All other model revisions and its objects will be disabled, and will only be available after the comparison is closed. To close a comparison, use the 'Reset button at the top (under 'Visual Styles').

While comparing model revision, creation of views / saving of markups is not supported. Any existing comparison needs to be closed to be able to start a new comparison. To close a comparison, use the 'Reset button at the top (under 'Visual Styles').

While comparing two model revisions, a 'Compare Models' icon will appear at the top. Clicking on this icon will show or hide the popup containing comparison details.

The 'Compare Files' popup will have options to switch between three options at top - base revision, compare revisions (Merged view of both revisions) and target revisions. The model view as well as the object tree will keep changing depending on what you select using each switch or toggle option, or when you select / unselect any model object from the 'Compare Models' view.

When the first switch button standing for base revision is selected, you can use three toggle options - Modified (Base/Target), Removed, Unchanged. In case of 'Modified' and 'Removed' options, you can also view count of modified or removed objects as applicable.

When the second switch button standing for compare revisions is selected, you can use all four toggle options - Added, Modified (Base/Target), Removed, Unchanged. In case of 'Added', 'Modified' and 'Removed' options, you can also view count of modified or removed objects as applicable.

When the third switch button standing for target revision is selected, you can use three toggle options - Added, Modified (Base/Target), Unchanged. In case of 'Added' and 'Modified' options, you can also view count of modified or removed objects as applicable.

Mouse over on the 'Base' and 'Target' button to find out the version numbers that are being compared.

You can also add objects to the object list while comparing models. From the 'Compare Files' popup, select the object you want to add using checkboxes, click on more options icon and select 'Add Object to List'. Other than this, you can export compare list in XML format by selecting 'Export Compare List' option. This XML format file can be opened and viewed using MS Excel.