Yes, they were all built to identical standards. But even then we had small differences, like Bette could run faster than Andrew. Not by much, and there was no reason for it. But it showed up in some of the games the units played. Also some units were better at some games than other units. I don't think that we can say there was much differences from one to the other, but even before each one got it own paint job, I could tell them without looking at the number plates.
I am like you, I think experniences had more to do with the personalities than anything else.
Dr.D