Why the card's ATR is different from a product to another one or from a firmware version to another one?
The ATR of a wired-logic storage card is constructed according to a list of card technologies maintained by the PC/SC workgroup
Let's use the MiFare UltraLight example, new versions of this list are published regularly, some couplers used to implement the 2005 version, where only the UltraLight is referenced.
Hence all cards that look more or less like a Mifare UL return NN = 00 03 "MIFARE UltraLight".
Today's couplers (CrazyWriter HSP for example) implements the 2011 version, where the UltraLight C has been added.
Cards that look more or less like a Mifare UL but with more than 16 pages return NN = 00 3A "MIFARE UltraLight C"
Tomorrow's products (including next version of CrazyWriter HSP firmware) will implement the last version at the date of release.
Today it would be the 2013 version, where the UltraLight EV1 has been added under NN = 00 3D.