Anyone know what the difference is ?

Hi Dave, welcome to the forum - I'd take a guess that it's just an updated/uprated version of the original.  

Do you reckon it means then that the old filters aren`t up to the job ?

No, my guess is that the manufacturer just changed materials or made some improvement to it, maybe ongoing R&D?

If your car is out of warranty, then Mann filter would be my suggestion 👍