The EV3 is the third generation Lego robot, released in August 2013 (in fact the '3' in the name indicates that it is the third generation and the EV stands for 'evolution'). The previous generation was the NXT, and there is a high degree of compatibility between the EV3 and the NXT.
Both the EV3 and NXT models have many characteristics in common, but there are also many differences... - The EV3 has an 'intelligent brick' running Linux and with much more memory than the previous (NXT) version.
- The EV3 brick is backwards compatible with the sensors and actuators (motors) of the previous (NXT) generation.
- The NXT brick is forwards compatible with the EV3 motors but not with the EV3 sensors.
- The EV3 software is compatible with the NXT brick.
- It's not possible to connect (daisy-chain) an EV3 brick and an NXT brick.
- It is possible to control the EV3 robot using an IPhone or Android phone.
 It is possible to program the EV3 brick directly without the need for an external computer.- It is possible to connect up to 8 EV3 bricks together.
- The basic retail kit will include instructions for building 5 different robots and instructions for many other robots will be available online.
- Only your imagination will limit the number of original designs that you can create.
- The price of the retail (home) version will be about 300 EUR in Europe.
There are plenty of good sites that cover the differences between the EV3 and the NXT. Here are a couple: | 