When to make a django app, rather than just a model
In your case, I think the better is to put your two models in one app.
Recently I've been making a few test projects in Django and while I've found the structure to be better than that of other Web Frameworks, I am a little confused on the concept of different 'apps'.
Here is a test case example:
Suppose I have a simple CRUD application where users post a picture and a title, with a small description, but I want other users to have the ability to create a review of this picture. 
Seeing as both the "Post" and "Review" models in this case require CRUD functionality, would I just have two models in the same app, and associate them with one another? Or have two separate apps with different urls.py and views.py files?
I have a hunch I've been doing it wrong and it should be just two models, if this is the case how would I go about writing the urls and views for two models in the same app?
Thanks and any input is appreciated!