In the Render View, the lighting and reflections from the HDRI map (IBL) and Area Lights are calculated separately and composited together. This is a short cut to improve the performance of the Render View, to make it faster and more interactive.
This does mean that in some situations the result may be a little confusing.
In this example below, we have the kettle lit with a HDRI map and an Area Light. Even though the Area Light is not transparent, and will not be transparent with this lighting setup in your actual render software, in the Render View the sun from the HDRI map can be seen through the Area Light reflection on the kettle. If this was physically accurate, the area light would obscure the sun, and would cast a shadow too. This is not the case in the Render View.
