There is a difference in the final drive ratio
1.0 = 4.471:1
1.4 = 3.895:1
The 1.0 litre is the best if you are running larger wheels and tyres or looking to fit this in a rally car with 13" wheels
If you can not tell which model if is from, remove the drian plug and carefully count
the teeth on the crown wheel. You can just about do it.
1.0 = 76
1.4 = 74