I have two sections(An HR section and an Approver section) in Infopath. I have a list of HR Users and Approver Users. How can I display only the appropriate section to the appropriate users?
I believe you are looking for the last piece of this article: https://social.technet.microsoft.com/wiki/contents/articles/32515.restrict-infopath-section-visibility-based-on-user.aspx .
The author seems to be illustrating roughly what you are trying to achieve.
Further more, if you get data using Web service, you can check this article:
http://eimagine.com/using-infopath-and-the-web-service-getuserprofilebyname/