Saint Laurent YSL Niki Bag

Is there a difference between the new niki ysl bag and the older version?

Also, i'm torn between the medium and baby size. Baby size looks cute and handy especially on crossbody style but would it be too small for traveling? Cant fit water bottle after phone, wallet and all essentials.
I have medium and love it. I know I have to stop overstuffing it, but I just love how much it holds.