WD Buy HDD new

Happy new year everyone.
I want to buy a new HDD. But, how can I discern who is blue or green from name WD?
I ask because WD christened blue several of the green series with their code you discern who is who.

Thank you

WD has not made green series disks for quite a while. Now the blue series are their lowest cost disks. Recently in Canada the 4TB disk is $99 shipped after more discounts.