What the difference between SOCIAL_AUTH_USER_MODEL(django-social-auth) and AUTH_USER_MODEL(Django)?
To override the default django user model use AUTH_USER_MODEL. To use django-social-auth with the new model point to it by using SOCIAL_AUTH_USER_MODEL. Both use auth.User by default.
A bit frustrated about this. 
What the difference between those options?  
Which I need to use to override default django user model?  
What the value SOCIAL_AUTH_USER_MODEL has by default?