It looks like I'm going to buy a Chang consuming unit. When I've looked in the different stores for Chang circuit breakers they appear to be different colors and I don't know why.

Which should I buy?

The images you have posted are of three different breakers.

 

First lot (purple) are 2-pole 20A MCBs.

Second lot are single-pole 32A MCBs.

Third lot are 63A x 30mA RCBOs.

 

Each has a different purpose.

 

You probably need an electrician to design your system.

 

4 hours ago, Crossy said:

You probably need an electrician to design your system.

And a college course in domestic electricity installation.

 

I think what Crossy is saying is you really shouldn't be trying to interpret that which you don't understand.