When a drawing is changed from one revision to another Inventor would have a view where you can show the changes between the two revisions. The best example for this is Microsoft Word. Where you have the option to switch on or off tracking.
View changes in various forms:
Simple Mark-up:
All Mark-up:
Then the option for the approver to accept the changes before the drawing is released:
There is also a log of the revisions:
In an inventor drawing this would possibly take the form of revision triangles which are left on the drawing once completed and simple notations to show if dimension values have changed, dimensions deleted or if any of the lines on the drawing have changed in size or shape.