All rides have height restrictions and you will be measured with a pole before riding any rides if you are close to the allowed height. Their colour chart board is only a reference. I did find some of the poles they use are not the same size, although the same colour category ride as others.
Just don't be too surprised if your child is just hitting the mark at one and allowed on, but not allowed on another of the same colour coded ride.
If you know you or your child might be close to one of the colour levels, maybe politely ask them to measure with the pole before standing in line.