Basically higher compression ratio , taller final drive, and better acceleration.
Cams are identical.
If the car has catalytic converter, the power is less than ECE rated output
Compression ratio -10.5 (ECE version); US from 1985: 9.7
Rated output - 185 hp / 136 kW at 6200 rpm (ECE version) US from 1985 177 hp / 130 kW (with catalytic 170 hp / 125 kW) at 5800 rpm
Rated torque - 235 Nm at 4500 rpm (ECE version); US from 1985: 230 Nm (with catalyst 220 Nm) at 4750 rpm
Final drive ratio - 3.07 (ECE version); US from 1985: 3.27
Ignition - transistor ignition (ECE version), US from 85: electronic ign. system
Acceleration 0-100 km/h (0-62 mph) - 7.5 s (ECE version); US from 85: 8.2 s (with catalytic 8.5 s)
I believe ECE versions also came standard with monotube front struts and slightly lower ride height.