Shell Rotella "Synthetic" vs. Shell Helix Ultra Synthetic

[outrun]

I am confused. Is the Helix the Group5 4 % 5 while Rotella is group III? What is this with the "wax isomerate" formulation?

 

[Al]

Rotella is group III . I believe the Helix (Ultra??) was Group IV. Helix More Helix