Which one does not belong?
Odd One Out shows a small group of items where all but one share something, and asks the child to spot the exception. It is a categorising exercise: to find the odd one, the child has to first work out what rule the others follow. That is a genuinely different mental move from matching or counting.
The 2-4 level uses very obvious differences between familiar categories, such as three animals and a car, drawn large enough to compare at a glance.