I have a question about Microsoft Team Foundation. In Visual Studio, Team Explorer, I can create a new work item. Work item types here are dictated by your team\'s chosen proces
It looks like you are using the Scrum process template. The TFS site has published some very brief information about Product Backlog Items and Features and the idea behind creating a new work item type. http://www.visualstudio.com/en-us/news/2013-jun-3-vso.aspx
The difference between the two comes down to what granularity you want to work with your work items at:
I have not been able to find any official guidance on when to use Features vs Product Backlog Items but I have created my own guidance which I am basing this answer on... http://www.nsilverbullet.net/2013/06/04/features-help-us-plan-work-better-in-team-foundation-service-scrum-process/
Should you create a Feature or a Product Backlog Item?
[Update 2014-05-19]
Microsoft have published more information on how to use Features and the agile portfolio concept that has been implemented in TFS https://msdn.microsoft.com/en-us/library/dn306083(v=vs.120).aspx