The Soul was changed slightly for 2014. The shoulder belt for 2C is now detachable – which means it has extra hardware where the lap belt is anchored, which can interfere with the installation of some car seats and boosters. The seat belt buckle for 2C appears to have gotten shorter – which should make it easier to install car seats with less likelihood of needing to twist the buckle to get a secure installation of the car seat. There is now an arm rest in 2C. Otherwise the back seat is identical to the 2011-2013.
For 2011, the head restraints for 2D & 2P were changed and are no longer ones that protrude over the vehicle seat back. Otherwise, the back seat is identical to the 2010.
The seat belt buckles for all 3 seats – but especially 2C – are on a long piece of seat belt webbing – you may find the need to twist the buckle stalk (up to 3 full revolutions) to shorten it in order to get some car seats installed tightly – as shown here. 
The Soul was first introduced in 2010. It has a wide, flat back seat that makes it better suited for side-by-side or 3-across than other vehicles in its size class (this will be less true as it gets redesigned and there becomes more prominent sculpting of the side seats). There are head restraints that are adjustable and almost certainly removable in all 3 seats.
The seat belt buckles for all 3 seats – but especially 2C – are on a long piece of seat belt webbing – you may find the need to twist the buckle stalk (up to 3 full revolutions) to shorten it in order to get some car seats installed tightly – as shown here.
