The main difference is that the PhysioCarrier 2 is an all-in-one solution (no accessories needed) with an adjustable-width seat to accommodate the infant's hip spacing and an adjustable central panel height for the child's size (similar to the PhysioCarrier).
These are two different solutions but equally physiological for carrying from 0 to 36 months.
The PhysioCarrier 2 is also made from high-quality cross-twill fabric. With the PhysioCarrier 2, you can also attach the straps under the baby’s bottom to better maintain their curled-up position and keep their limbs grouped together. The strap loops prevent contact with the baby’s legs.