SmartTarget and Profiling and Personalization are not the same although at a very very basic level it may appear you can force them to do the same thing.
Profiling and personalization will allow you do display specific Component Presentations (attached to the page) to be displayed on the page if the profile logic is met.
SmartTarget integrates with the very powerful Fredhopper and based on the (extensible) rules your marketer (the main target for this interface) implements in SmartTarget then certain Component Presentation(s) will be returned accordingly.
Bagging Profiling & Personalisation and SmartTarget/Fredhopper together grossly understates the power that SmartTarget offers the business; I'd suggest you reach out to SDL and speak with the pre-sales or training guys.
Audience Manager (again - this isn't a sales pitch so excuse the brevity) is, at its most basic, a contact management tool.
- Profiling & Personalisation: you manage the Presentations on the Page
according to simple categorisation of the visitor
- SmartTarget: Frontend to the extremely powerful ecommerce engine Fredhopper,
extensible and its real power is in managing rules that will result in the 'contextually correct' content to be delivered (from Fredhopper - which receives the CPs from the CMS)
- Audience Manager: You explicitly know a contact and have their details stored here
Regards the upgrade - I know that profiling and personalization is still available in 2013 SP1 so can't see any reason that it wouldn't upgrade fine - this, of course, depends on any custom code/configurations you may have implemented.