Rolex

I've been looking around at a used sub and noticed that there are many in the series and was wondering if anyone know the differences?

A, W, Y, Z series.

Thanks in advance

The only differences is there will be solid endlinks at the bracelet and not
lugholes straight thru the case. The laser logo at the crystal and engraving
ROLEXROLEXROLEX at the rehaut.

thanks, appreciate the info