Object variants provide a flexible means of creating and maintaining variations of a single object.
Variants are linked to a book through their primary, or parent object, and unlike versions, you can have multiple variations of an object active at any one time.
Variant criteria values control which variant object is used in each adaptation of the book. For example, you can base your criteria on location (country, state, or city), product version, supported platform, and so on - you define the criteria appropriate to your content.
Use variants when updating content for product releases. By using this method, you continue working in the product's main book and create variations of the topics that require updating for the new release. When you need to publish the book, just select the criteria for the chosen release. Your published book contains the standard content (which hasn't changed) and, where appropriate, the content for the new release.