plone.app.portlets provides a Plone-specific user interface for plone.portlets, as well as a standard set of portlets that ship with Plone.
plone.app.portlets 2.4.x is for Plone 4.3. plone.app.portlets 2.5.x is for Plone 4.3 with plone.app.event (makes the calendar- and events-portlets use the p.a.event implementation) plone.app.portlets 3.x is for Plone 5.