EAN-13 and UPC-A are using the same encoding scheme and both contain 13 digits.
However, the UPC-A barcodes do not show the leading zero of the barcode which is a country code indicator for North America.
Scandit provides a symbology extension for the EAN-13/UPC-A symbology to remove the leading zero from the result:
More details on the symbology extension can be found here:
In case you want to read more about EAN-13/UPC-A, please see the following document: