I have some alvas. Not any of the special ones (no double gussets, no bamboo liner). I've used them on my lo since she was 6 months.
For the most part the different series just means when they came out with new prints. I no longer even see double gussets as an option.
So nothing really outstanding or different between the series except regular pul and minky. But if you click on one of the series it will say if the prints are minky or not.