This appears to be a sometimes a confusing subject to SharePoint consultants alike. Should you recommend variations or use audiences.
Variations allow you to target "content" to specific people i.e. audiences on different sites. So in essence:
- Content created on Site A
- Content is now replicated on Site B
The core benefits of using variations is to be able to affect the display of information from one site to another. So for example, we could have content in Site A originally created in English, but then have Content on Site B being displayed in a foreign language using a language pack addressed to that Site. Hence, the display of information for site A is displayed differently on Site B.
The list goes on and on from designing target sites with different font sizes i.e. a site for disability access, or sites for mobile devices only. Some folks in the industry have began to call variation sites as reference sites.
So how does this all contrast with audiences.
Well its different in the sense that whilst variations controls the way in which data is displayed from one site to another, audiences on the other hand allows organisations to target content to end users based on their job roles or tasks. Audiences can evolved from the following:
-Membership in a distribution list or Windows / SharePoint security group
-Location in organisational reporting structure,
-Public properties in user profiles.
How to use audiences -
-a User Profile service administrator can define the links that display in the SharePoint locations, and set the audiences that each link is visible to.
-On My Site Web sites, a User Profile service administrator can set audiences for the My Site navigation links that appear on the top bar.
-For My Site scenarios in which users must have access to one or more additional My Site host locations, a User Profile service administrator can manage a list of Trusted My Site host locations, and then target each trusted location to the audiences that need to view it.
In an environment with multiple My Site host locations, audiences also determine in which trusted My Site host location a My Site Web site is created.
-In an environment in which a User Profile service application and audiences are configured, site administrators can use Web Parts to target content by audience.
-Site administrators can use SharePoint groups to target content to Web Parts both in environments that are running a User Profile service application, and in environments that are not running a User Profile service application.
So in essence variations affect the display of information from site-to-site while audiences is used to target or control access to information on SharePoint site.