All these roles have the same privileges, but correspond to the roles within the real class. The pretty name for these roles titles can be changed on a per-group basis through the group control panel. Also, course administrators display on the members portlet, but not in the staff list portlet.
Thank you Deirdre!
I thought that they haven't the same privileges, but now it is clear that TA, CA and CAdmin are just synonyms with corresponding roles within the real class.