EAN/UPC is the collective name for the barcodes EAN-13, EAN-8 and the American variants UPC-A and UPC-E.
This type of barcode is mainly scanned at the checkout (and possibly in a logistics environment).
In the EAN-13 barcode, a GTIN-13 is encoded.
The EAN-8 barcode is used on small packages, when an EAN-13 barcode is too big. In this barcode, a GTIN-8 is encoded.
UPC-A and UPC-E are used in North America to identify products using a GTIN-12. Outside of North America, these variants are rarely used. The EAN-system and the UPC-system are, however, compatible.