And instance of difference clean_data

And instance of difference clean_data

First, clean_data and form of the object instance is called

grammar:

clean_data:
    form_obj.clean_data [ ' attribute value ' ]

instance :
    form_obj.instance. Property Value

the difference:

We can understand:
     clean_data is a front end input (not necessarily input, may be other) inside the value, from the front end to get data 
    instance is the value of the back-end database, from the rear end to get data