In the following question, out of the four alternatives, select the alternative which is the best substitute of the phrase. One who values practicality
Use SAVE when you want to update the lastly preserved or to revise an existing document or file with the latest content.
Whereas
Use SAVE AS when you are creating a new document/file or an existing document/file to a new location. This will keep the original document untouched in its original format and create a new document with a new name.