Jodi - yep, the fabric on the Ergo Organic is 100% organic cotton, the regular Ergo is poly cotton (non organic) blend...The fact of using the organic cotton is well worth the price difference IMO.

Kate - The Sport is about 20% lighter than the regular Ergo, more compact a design, and only comes in the black (so if you want colour etc the Organic or Original Ergo will be more your speed.

I have used all of them and for ease of use and space and storage etc my fav is the Sport. Hubby likes the Sport too, although having said that the Organic one s comfier for longer periods - my Sport is the "lives in the car carrier".

HTH