admin interface / CRUD interface - they are easy to generate but easier to customize under symfony. - you can do 90% of the stuff via a config file generator.yml. The rest is extending the generated code and customizing queries to the model
configuration - you can do more via the config files in Symfony and control your project/applications vs Django.
forms system - the abstract forms system comes with generated forms based on your model, widgets with validations, binding with your model, customizable renderers. You can have a custom CRUD interface up and running and linked to your tables in less than a few minutes.
routing - routing.yml and sfPatternRouting does a much better job without using complex regex patterns - Also, all routes are abstract, understandable and well located.
testing - Unit testing and functional testing is very well done. You can launch specific tests, launch failed tests only, call your model/forms easily because they are all objects, simulate a browser session etc. You can do all that stuff with Django but will a lot more code.
framework vs API - symfony abstracts anything useless as a plugin where Django tends to integrate some of it in their Framework (CSV, PDF generators etc.). That's a lack of vision.
Anyway, just a couple of points, I could go on and on ;-)