2e engine is similar to later engines but it has no crank sensor. it does have oil squirter for the pistons which iirc the later ones dont have. i have read that the later engines have a better (forged?) crank.
the later management is more sophisticated, with a crank sensor so no more ignition timing to deal with, no isv instead using a stepper motor inside the throttle body. injectors are different on the later engines too, the 2e code uses odd shaped injectors built into a plastic fuel rail, the later engines switched back to the more universal and widely available bosch type injectors and use a metal fuel rail.
reliability wise early system has less to go wrong, but the later system requires less in the way of tunign as all the ignition timing is done automatically. with the 2e you need to move the dizzy to the right spot, with later ones you set it to exactly TDC and leave it there
