ok everyone, I shall explain the difference between barrier series ans the shield series.
Barriers series as I see it, aims to improve the actual shields from each element: Jade shield, Phase shield etc.
and I assume as Zblader stated, They aim to create new types of mechanics such as creature protection, etc.
Shield series recently became a series that does NOT improve each shield individually. It aims to be an "extra effect" for "any" shield, therefore they can stack ontop of each other for a single shield. This is still under discussion though I think thats how its going to be, although it still needs some balancing out, this was only recent.
I will soon create a seperate series thread for it in card ideas section.
those are the differences as stated above.
I see these two as either 2 different choices for the community or possibly working together somehow in the future since in concept and mechanics they are similar but not quite the same if we go into depth.