SharePoint Apps vs Features

Question

SharePoint 2013 supports new kind of Solutions called Apps.According to MSDN, Apps are self contained piece of functionality and easy to install, use and update.

I think SharePoint features also support easy installation and upgrade. A feature can contain self contained functionality like web part or timer job.

Then,What is the difference between Apps and Features or the traditional Solutions (Farm or Sandbox)

Answer 1

In an app:

• all the SharePoint artifacts you create (lists, pages, files) are located in a special sub site only for that app.
• all the code runs outside the SharePoint servers, can be client site, other servers or Azure
• for the code to access items in the original site/site collection, the app have to specify that in it's manifest and the installing user has to have these permissions and pass them to the app
• one app has absolutely no access to the data of another app

So the advantages for apps are:

• They are really separate from the site where they are installed which makes it easy to uninstall (can remove everything)
• Can't affect perfomance of SharePoint servers
• Can do more than you could in Sandboxed solutions

The disadvantage for apps are:

• Completely new development model, which at least in the beginning will be a lot harder.
• No way to combine apps to work together

Answer 2

This article on MSDN goes into detail, but sums it up succinctly as : "Apps are for end users and farm solutions are for administrators." Sandbox solutions are deprecated with 2013, and generally the sort of thing that you would have previously used a Sandbox solution for should now be an app.