What is the difference between " Import My Organization Contacts" and "Import My Contacts"?

What is the difference between " Import My Organization Contacts" and "Import My Contacts"?

Import My Contacts
The records will be assigned automatically to the person who is importing the file into Contacts Tab.

Import My Organization Contacts 
You can assign the records to different users in your account while importing the file into Contacts Tab. However, before importing the organization contacts you must create a column for the Users in the XLS or CSV file.