I am developing a django project. I created some apps, some of those are related to User model, for instance, I have a feeds app that handles user feeds, and another app that deals with extra user data like age, contacts, and friends. for each of these, I created a table that should be connected to the User model, which I using for storing and authenticating users.

I found two ways to deal with this issue. One, is through extending User model to be like this:

ModelName(User):
    friends = models.ManyToMany('self')
    .....

Two, is through adding a foreign key to the new table like this:

ModelName(models.Model):
    user = models.ForeignKey(User, unique=True)
    friends = friends = models.ManyToMany('self')
    ......

I can't decide which to use in which case. in other words, what are the core differences between both?