The main difference as I understand is the rise and I think the bit in between the legs is slightly wider with the toddler. I was supposed to be only getting toddler sizes to make sure they last but have been too tempted by the beautiful M/Ls on Etsy. DD is still on the tightest snaps with her M/Ls. I should get a couple of toddler sizes in the next couple of days so I can let you know.... I will also look on the Yahoo group as I am sure that this has been discussed on there recently.
ETA: The discussion said what I just said!