Google - The Difference Between 'Add to My Drive' and 'Make a Copy'
When you open a Google file shared with you and select 'Add to My Drive', you are moving that file into your own Google Drive for easier access to the document. If your instructor or someone else owns the file, any changes they make to it will be updated in the file housed in your Google Drive. It is a living document that is updated in real time. If the owner of the document deletes the file from their Google Drive, the file will be deleted from your Google Drive.
When you 'Make a Copy' of a Google file, you are duplicating the original document and making your own copy that you can edit, share with others, etc. Any changes you make to your copy will not be reflected on the original document owned by someone else. In addition, any changes the owner makes to the original file will not be reflected in your copy.
Google - How to Share a Google Doc
Google - How to Submit an Assignment from Google Drive to the Canvas Student App on an iOS Device
Google - Syncing Your Commons Account with a Google G Suite Account
Google - Training Resources
Google - How to Change Editing Permissions on a Google Doc
Google - How to Convert a Google Doc to a Word Document
Google - How to Submit a Google Doc Assignment to Canvas
Google - How to Convert a Google Doc to a PDF
Google - How to Save a Copy of a Google Doc My Instructor Shared