What is difference between Euro 2 and Euro 3 engine?

1) Euro 2 has a small turbocharger whereas Euro 3 has a big turbocharger.

2) In case of Euro 2 engine Return line of fuel is below the intake manifold whereas in case of Euro 3 engine it has above the intake manifold.

3) Euro 2 has 5 holes in the injector nozzle whereas Euro 3 has 6 holes.

4) In case of Euro 2 design of intake manifold is not controlled by ECM whereas in case of Euro 3 it is sophistically controlled.