What is the difference between the pick and pickAndStore methods of the v2 library

The main difference between pick and pickAndStore is that pick can generate symbolic links to where the file is originally stored on the web, and pickAndStore will always make a new copy of a file. A symbolic link hooks directly to the file where it is located. If that is a person's Dropbox account, and that user deletes, renames or moves the underlying file; the Filestack link will break. PickAndStore makes a copy of the file, so unless you delete it or make some change to it on your end, the Filestack link should remain valid. To read more about the different behavior of the pick methods visit this page: Pick vs Pick and Store - What is the difference?.