Unfortunately there is a lot of obsolete or inaccurate terminology in use. Here are some pointers to avoid common causes of confusion...
Numbers: The numbers are correctly called Global Trade Item Numbers or GTINs. Calling them "barcode numbers" or worse still "barcodes" is wrong and will lead to confusion. The same GTIN may be encoded in a variety of different barcodes.
Barcodes: These are the printed symbols in which the numbers are encoded. There are several different types or symbologies used in various scanning environments such as retail or distribution. The most common are....
EAN-13 - used in retail and distribution
UPC-A - the original American barcode, also used in retail and distribution
(The retail barcodes are sometimes collectively known as EAN.UCC barcodes).
ITF-14 - used only in distribution, cannot be scanned at retail
GS1-128 - used in distribution where additional information such as batch number or use-by date is included with the GTIN in the encoded data. GS1-128 cannot be scanned at retail.
Download the Basic User Guide for details of correct standards and terminology.
The following terms are wrong but are in widespread use and cause endless confusion. Their origins lie in old GS1 terminology that is now obsolete or in company jargon developed in industry and now entrenched. You should avoid them.
TUN or DUN - wrongly used for both the numbers and the barcodes on shippers.
APN or EAN - wrongly used for both numbers and barcodes on retail items and shippers. Sometimes "EAN" will be wrongly used to mean a GS1 barcode verification report.
Scans - as in "This barcode scans" or "...doesn't scan," when the speaker means that the barcode passes or does not pass the GS1 barcode verification test. A barcode that fails the verification test may still scan ordinarily.
Version 1.0 5 Jun 2015