EV3 offers 3 new features compared with EV2

• New possibility of deleting applications via DAMMAC
  A new possibility of deleting applications in the badge is proposed in EV3 by delegating this permission with new DAM keys.
  This can be useful for uses that require more dynamic badge management by deleting applications that have become useless, for example: a preloaded credit application, when it is used up, I delete the application and should create a new one when reloading, thus offering the possibility of different settings.

• Secure Dynamic Messaging and Mirroring
  This functionality, which has become dynamic compared to EV2, reinforces the security of data transactions between the badge and the system.
  This new functionality is not supported by access control systems today. It will come, but only for the most sensitive sites.

• Transaction Timer
  This is a 100% new feature in EV3, designed to prevent Man-in-the-Middle (MitM) attacks.
  This reduces the risk of someone standing in front of the reader with communicating RFID equipment, and a second person standing near the badge with the same type of equipment, but miles away from the reader.
  The (already highly advanced) system would work like a radio bridge, making the reader think the badge is in front of it.

Backward compatibility within the DESfire family is total.
So EV3 can be used in the same way as EV1, EV2 and D40, just as EV2 can be used in the same way as EV1 and D40.