Many people are surprised to learn there can be gradings and belts in tai chi. This is because many clubs don't do them, but instead focus on the health aspects of tai chi. Then again some clubs which do include the martial aspects, don't do gradings  either, but have their own  systems of encouraging progress.

Those clubs that do do gradings don't necessarily use the same colours for each stage, but instead can arbitrarily decide on whatever colours they like and whatever stages they like. This means you don't have a rigid heirarchy, but instead go along with the flow of whatever your club does.

For the club I belong to, I do adult beginner gradings and kid gradings. While there are similarities between the two, there are also differences:

With the adults, it's often the very first sporting achievement and a real ego-boost as a result. Many adults (myself included) were  distinctly unsporty at school, so achieving a grading and wearing a sash as a result, is something very special.  Other adults are more sporty to start with, so for them there's not so much of that specialness, but still there's that nice feeling as their achievement is recognised.

The adult grading is also a teaching experience, rather than a grilling exam experience. This means that it's designed to help bring out what people know and celebrate that, as well as to help focus them on how to improve on whatever specifics. Thus it's a very useful aid to continuing progress being made.

Kid gradings have variations in content from the adult  gradings, which comes out of how I teach the kids class. I've finished  writing my book on this and am  just thinking about what photos to include, before it goes to publication. Essentially though, a kids class will include more activities, as kids attention spans are shorter (until they've been subjected to my attention span increasing techniques), so this will have knock on effects:

Starting with looking at the adult gradings, then this was adapted to produce a kid grading set that includes all the extras the kids do. For instance, while adults learn competition push hands as separate to a main beginner lesson, it is an integral part of a kid lesson, so the grading will incorporate techniques for this into it.

With the kid gradings, I  also send out the list of items in the grading  to  the parents, in advance. This allows the parents to encourage their kids to practise. It also means those parents who do tai chi themselves can practise these specific things with their kids too.

Also with the adults, there's a feedback session as part of the grading. But with the kids there's a ceremony instead, where the kid gets presented with their sash and pictures taken, etc. All great fun!