They brake and power up differently, I believe it has to with dynamic braking. But as for everything else they are the same, The Material the R142 has doesnt seem to get as easily dirty as the R142As, But then the R142As look alot shinier, with good care, the R142A can outshine the R142.
As for which train is better, It is PURELY based on opinion. No one train is better then the other. I can say the R1 is better the R142A and believe that the R1 is in much better condition the R142A. Again, Its all opinion. There is no right answer.