Sami,
All the distance-specific Premium Strength plans are exactly the same with the exception of duration. The Level 0, Level 1, etc. represents which level of the primary plan the Premium plan should be matched to. Particularly the triathlon plans, which differ significantly in duration, the duration of the Premium plan levels match the duration of the triathlon plan levels. So, pair a Level 1 Premium Strength with the Level 1 primary plan, etc.
In your case, the Level 0 and 1 70.3 primary plans are exactly the same duration, so there is no difference at all!
David