One SQL Server 2014 giving different password hash
This is because since SQL Server 2012 the hash algorithm has changed.

Starting from this version, the hash is twice as long.
You can read up on the three hash versions that are used for the various versions of SQL Server in the sp_help_revlogin microsoft article, under Remarks:


  A password can be hashed in three ways:
  VERSION_LEGACY: This hash is a 16-byte pre-SQL Server 2000 hash.
  VERSION_SHA1: This hash is generated by using the SHA1 algorithm and is used in SQL Server 2000 through SQL Server 2008 R2.
  VERSION_SHA2: This hash is generated by using the SHA2 512 algorithm and is used in SQL Server 2012.


Which means that if you want to move a SQL Server 2012 or higher user to a 2008r2 instance, you'll need to find a different method.



I tested it quite a bit now. Any user created under SHA1 when moved using the password hash to a new version server (2012+) can then be moved back as long as the password isn't changed. However any new user created in 2012+ will not be moveable to 2008r2 or prior.