The 18-270mm gets three more initials added to it's nomenclature (18-270mm f/3.5-6.3 Di II VC PZD) with the addition of a Piezo AF motor to replace the older standing wave motor. I've noted several times recently that Tamron's in-lens motors aren't as fast as the Nikkor or Sigma ones, so let's hope this brings them up to speed, if you pardon the pun. I understand that the lens should be in the US just prior to Christmas (Dec 20 or thereabouts).