The word "Glatt" or "Chalak" in Hebrew means smooth and it is a stringency in Jewish Law which many people follow (myself included). The term means that there were no questionable lesions on the lungs of the animal slaughtered and, subsequently, the percentage of Glatt meat is much smaller compared to that of "regular" Kosher meat and it is more expensive. All Glatt meat follow the same basic criteria, regardless of whether the meat was slaughtered by an Ashkenazi or Sephardi shochet. Regular Kosher meat may have had questions raised about the standard of its Kashrut but the Kashrut body overseeing the slaughtering ruled that the meat is Kosher. The concept has existed for generations and it is codefied in the Shulchan Aruch.