An apparatus is defined as
Physiology. a group of structurally different organs working together in the performance of a particular function.
An organ is defined as:
Biology. a grouping of tissues into a distinct structure, as a heart or kidney in animals or a leaf or stamen in plants, that performs a specialized task.
The below shows the Juxtaglomercular apparatus (JGA). Without knowing its name, how would I tell if it is an apparatus or an organ?
There is a question in my book (which asks: which organs are necessary for the continuation of the Renin-Angiotensin-Aldosteron-System) and to answer it correctly requires that we know that JGA is an apparatus and not an organ.
Is there any giveaways that show it is an apparatus and not an organ, based on the diagram alone?
I can't really tell based on the definitions above e.g. based on the diagram, I cannot tell if JGA performs "a specific task" or a "particular function".